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to test and approve its genuine flavour. A certain stringiness, however, will sometimes appear from the milk jug, and float upon each cup of tea, or coffee, as the case may be; and the good people, amusing themselves with the news of the morning, cast a passing glance at the ropey appearance of the fluid, and, fancying it richness of quality, the mixture is swallowed with gusto. Various other modes of improving the milk are said to be adopted by artists in that particular way; but with respect to London, the writer in the Lancet gives us comparative comfort, for it is stated that in 26 samples of milk that were examined, none were found to contain any thing but the admixture of water, the quantity of which may be ascertained by the lactometer, and it was proved that of these samples, two or three were genuine in the others the quantity of water varied from one pint to nearly two quarts in a gallon of milk.
say, let them no longer be allowed to incarcerate the animals in such dens of filth and suffocation, within the bounds of the city and suburbs. Now that the facilities of transit are so great, five or six miles are not an object compared with the great advantage of health to the animals and the wholesomeness of the beverage they supply.
Let us examine the next article of sustenance,-" Our daily bread." When potatoes were cheap and bread dear, the adulteration with boiled and mashed potatoes was more common, I believe, than it is now. The objection to it is, that potato-flour is not so nutritious as that of wheat. Bread is often adulterated with rice-flour, which enables the bread to absorb and retain a greater quantity of water. In this way the consumer is cheated of a certain amount of nutritious wheat farina, the place of which is supplied by water. A more general adulteration is pracWhat the contents of the London water are, with which tised, I believe, in the use of alum, which has a twofold the water companies supply us, the microscope has shown object: First, it renders inferior flour in colour and quality to be by no means calculated to improve or purify our milk. equal in appearance to that of superior quality; and seTwo eminent medical men, Dr. Lankester and Dr. condly, the flour retains a larger proportion of water, and Hassell, have analysed the water supplied by the several the bread, of course, weighs heavier. Some bakers buy companies, and published the results of their labours, rock-alum in powder; and some, an article known in the which amply show the necessity that exists for some trade as hards," and "stuff,"-this is a mixture of alum purer source of supply. The Artesian wells which supply and salt. The worse the flour is, the greater proportion of the fountains in Trafalgar-square tell us that there is "stuff" is required to make it good in appearance; in abundance of pure water under our feet, but the blessing some instances as much as sixteen, and even twenty is denied to us, and we are compelled to pay a high rate ounces to the sack of flour. The bakers say the public for a sadly impure article. Our cisterns are full of animal will have very white bread, and that it cannot be made life; of course there must be something in the water for without alum; but a white bread may be made with good those animals to live upon. We daily boil down mil-flour, and it were better not so white than mixed with lions of animals, and much filthy matter in our tea-kettles ingredients prejudicial to health. In 24 samples of bread and cookery, because the "vested interests," as they are from different bakers which were examined, not one was called, of selfish monopolists must not be interfered with! without alum. But for this, we might have a series of Artesian wells from west to east along the north side of London, which would amply supply our immense population with the pure element for every purpose in life.
But, to return to our milk for a few moments. It is difficult to procure good healthy milk, even when not adulterated. Indeed, it is vain to expect it while cows are kept in close, confined sheds, and do not breathe the fresh air, nor see a green field for months together-where the want of ventilation and drainage subjects them to the effects of a poisonous atmosphere, in which, surrounded by heaps of dung and other filth, they languish and die of disease. The microscope will show that the milk from such cows is unfit for use.
Our tell-tale microscope says that the cruet-stand is not free from contamination,-that our pepper, mustard, and vinegar are frequently no better than they should be, or rather, not so good. Various adulterations of pepper have been detected. Black pepper is the inferior small shrivelled berries, and often little more than husks, sometimes adulterated with burnt crust of bread powdered. White pepper is the berry divested of its outer coat, the fine granules towards the centre being the most pungent. Pepper being most frequently bought already ground by the consumer, there is every opportunity for adulteration. It is sometimes mixed with powdered husks of mustard. The late Dr. Pereira found sago mixed with white pepper, but that is easily detected by the microscope, the starch There is a small treatise on this subject, entitled " Ob-grains being larger than those of pepper. Other substances servations on London Milk" by Mr. H. Rugg, Surgeon, introduced to our pepper-box are, linseed, mustard-seed, published by Bailey and Moon, setting forth the various wheat-flour, and pea-flour, the sweepings from pepper abominations of this kind that exist in our modern Babylon warehouses, called P.D., or pepper dust, and an inferior called London. Another pamphlet is by the Honourable kind of this, called D.P.D., or dirt of pepper dust. H.P.D. F. Byng, "On the Sanatory Condition of the City of means hot pepper dust. These may be suspected in pepWestminster," in which he describes a shed under the pers which have a dry earthy appearance and an undue Adelphi arches, where the poor beasts never saw the light quantity of husk when the pepper is darker than usual. of Heaven from year's end to year's end, the place being But even if we purchase our pepper whole, we are not lighted entirely with gas, and the only ventilation that quite free from adulterations. The ingenuity of man existed was a small hole not half a foot square, knocked manufactures artificial peppercorns! In Accum's second through the wall that forms part of the lane that leads to edition of "Death in the Pot," he tells us that these are the halfpenny steam-boats. composed of oil-cake, common clay, and a portion of Cayenne pepper, fomed into a mass, and granulated by being first passed through a sieve, and then rolled in a cask. With what tenacity our mustard will sometimes hang to the spoon; it is like thick paste, and has not much pungency. "The most common adulteration of mustard is with wheat-flour, and, by some means or other, turmericpowder is made to part with a portion of its colouring matter to the flour which enters so largely into the composition of the mustard of the shops.' "In the manufacture of vinegar, there is sometimes a greater proportion of sulphuric acid than is allowed by law, and a smaller pro. portion of acetic acid than there should be. Vinegar, to be good, should not contain less than 4 per cent. of real acid. The sulphuric acid, it appears, is not necessary, though often added for adulteration; to prevent the ill
A great deal has been said and written about sanatory measures; but I conceive that the legislature would be beneficially employed in passing enactments to insure a good supply of pure water and healthy milk, articles of such paramount necessity, especially in all great cities and towns. If monopolists and their vested rights must still have a name amongst us, let the filthy water companies be compelled to adopt the Artesian-well system, and put to shame the ridiculous deprecation of Dr. Hassell, who, for some reason best known to himself, sides with them, and, suggesting a plan which would only continue the nuisance, he talks about "the merciless boring of the earth," as if the earth were a sensitive animal, and might come under the protection of the Society for the Prevention of Cruelty to Animals. Of the cow-keepers, I would
effects of which, the retailers (in compassion for their cus-trations of the method of examining it in a small fish and tomers, no doubt) add some sour beer, or cider, or even water. But this is rather an article for chemical analysis than for the microscope; as also our beer. A late conviction at the East-end of London has shown us that our malt liquor does not escape the general pollution; the poor man's beer is first killed with one-third water, and then resuscitated with a quantity of sugar and salt. Some have been known to hang a bunch of tobacco in the cask, ostensibly for fining the beer, but really to give it an intoxicating quality. What is called "finings" is occasionally supplied by the brewer. We sometimes like a little ginger in our beer, and for other purposes; but if we buy it ground, we cannot depend on its genuine quality. It is often mixed with sago-meal or potato-starch, or wheatflour and Cayenne pepper;-different samples vary-some are compounded with ground rice, cayenne pepper, and mustard husks, sago changed by heat, wheat-flour coloured with turmeric, &c., &c.
I should weary you by detailing all the metamorphoses that things undergo in the way of trade and manufactures. In these last the microscope has been successfully applied to the examination of various textile fabrics. The different fibres employed having each a distinct character, it may thus be determined whether that which is purchased for linen-cloth, or for silk, is entirely composed of those fibres, or has any mixture of cotton or other material, so that the composition of any mixed fabric will at once be made evident to any one who is acquainted with the microscopical structure of the materials made up, and often sold for what they are not.
By way of relief from deceptive appearances let us examine another substance which has become an article of rather extensive commerce. Some ladies, who may not happen to be very deeply initiated in the mysteries of science, would scarcely dream that the sponge with which they lave the delicate limbs of their charming little infants, is an animal, once living and breathing some fathoms under the surface of the ocean, affixed to a rock by an expanded base or stem, where it vegetates, or rather animalizes, like an oyster, in one spot, from the time the wandering gemmule leaving the parent sponge, finds a resting-place, until, full grown, the rude hand of the diver seizes upon it for commercial purposes. Still less would they imagine that this very useful animal, which, when wetted, is beautifully soft and luxuriant to the touch, when applied to the fairest and most delicate skin, is, in some cases, full of sharp prickles, whose points are fifty times finer than the finest needles that ladies ever worked with; yet the microscope tells us that this is one of the great facts of nature. However, there is not much cause for alarm from this circumstance, for, though numerous, they are so sheathed in the horny net work of the sponge that there is no danger of inconvenience from its use; and, in the next place, they are so minute that if any get loose, and penetrate the skin, even of an infant, they would have about as much effect as the sting of a bee in the hide of an elephant.
I will now return to one of the earliest and greatest discoveries in physiological science, namely, the circulation of the blood. Harvey, who is said to have discovered the circulation, never saw the blood in actual motion, although insisting on it. He argued, from the existence of valves in the heart and in the veins, their structure, and peculiar arrangement; "that the blood must flow from the heart, through the arteries to the veins, and from the veins back to the heart again, yet he knew nothing of the connecting vessels called capillaries." All that is now known of these minute vessels, the microscope and the beautiful art of injecting them with coloured fluids has supplied. Malpighi first made the discovery of the capillary circulation about the year 1661, by the microscopic examination of the bladder of a frog, and since then his discovery has been confirmed by many other observers. Leeuwenhoek, the father of microscopic discoveries, has, in his works, given descriptions and illus
in an eel. In later times the frog has been principally used for the purpose, and with acromatic lenses it may be witnessed in some of the smaller mammalia-in crustacea, and even in polypiferous zoophytes. It may be seen in the legs of some spiders, and in the transparent wings and antennæ of insects; in the tail of the small fish called stickleback; in the feet and tail of the water-newt, and in the web of the frog's foot. A more beautiful sight is the circulation in the lungs of this animal. By dipping the frog into water at the temperature of 120°, all muscular action is stopped; the animal is rendered rigid, but the circulation will continue for a long time. "When the body is opened, one of the lungs must be taken and bent over on a piece of glass placed on the stage of the microscope," and, as Professor Quekett proceeds to say, "the magnificent sight then disclosed will baffle all powers of description."*
In the mammalian class, the wing of a bat or the ear of a young mouse will show it, but the mouse is apt to be troublesome. A little chloroform, however, will quiet either him or the bat, without stopping the circulation of the blood. Perhaps the most novel and elegant object for illustrating this phenomenon is found in a young trout when only three or four days old, and it is the more delightful to witness from the circumstance that it can be shown without confinement or suffering to the animal itself.
In the spring of 1849, I had an opportunity of beholding this beautiful sight, and of making a set of drawings from it. At that time it was introduced to the notice of the Microscopical Society, by Mr. Samuel Gurney, jun., of Carshalton, where that gentleman had, after the plan of Mr. Boccius, succeeded in hatching numerous ova of the trout. The early stages of development of this animal takes place within the egg, and after a period of about forty days the young fish emerges from it, but remains attached to the yelk bag, which affords him nourishment until he is able to provide for himself. A reference to the drawing and diagram will show his mode of existence at this early period, when he is about three or four days old, and scarcely half an inch long. The circulation may then be seen to great advantage. The pulsation of the heart-the rapid flow of blood through the arteries, and its return by the veins in every part of the transparent body, is an exceedingly beautiful sight.
Another grand discovery effected by means of the microscope is that which is termed ciliary movement. Here, again, we find Leeuwenhoek foremost in the discovery; he noticed the cilia in the volvox, and recognised their use. Baker, in 1744, described them in the wheelanimacule, and made a distinction between their rotatory and vibratile motions. This minute but extraordinary animalcule excited the most intense curiosity, and long remained a puzzle to philosophers to imagine how it was possible for any animal to turn its head swiftly round continually in one direction, as this creature appeared to do, having at the anterior part of the body two small organs like wheels, and, like them, apparently moving on their axes. This motion is now well known to be an optical illusion. The apparent wheels of the animalcule are two circular rows of cilia, which have a waving motion given to them by means of the muscular apparatus employed. They do not wave simultaneously, but successively, round the whole circle, thus giving the appearance of a wheel in motion. This may easily be understood by supposing ourselves standing on a rising ground, and looking at a field of ripe corn, on a fine breezy day, with the wind blowing either from the right or left of the field with respect to our position. shall then witness the beautiful undulating motion of the corn, those undulations moving forward across the field like the waves of the sea. But we know that neither the
"Quekett's Practical Treatise on the use of the Micrc. scope," page 372.
corn itself, nor the waters of the ocean, do actually move Mr. Busk, and the other by Professor Williamson. Both those forward as that wavy appearance does, which is caused gentlemen advocate the vegetable nature of the Volvox. by the successive bending down of the ears of corn as Time will not permit noticing their arguments at length: the wind passes over them. So it is with the wheel- indeed, to do so might seem here, a dry detail of technianimalcule ("to compare small things with great"), the calities; and notwithstanding the decisive manner in successive action of the muscles bending down the cilia which the subject appears to be disposed of, the matter so rapidly, that the appearance to the eye is that of ro- still appears doubtful. It is very remarkable in those tatory motion. The purpose of this motion is to produce papers that, while detailing certain minute particulars a current in the water--a sort of "miniature whirlpool," relating to the structure of the Volvox, they avoid which brings whatever particles of matter the water any allusion to the natural habits and evidences of may contain within reach of this voracious little animal- vitality which these beautiful creatures exhibit. Now it cule, who, itself not above one-36th part of an inch long, appears to me that in our search after truth, we should creates a whirl in the water many times its own dia- always scrupulously examine both sides of the question. meter, and in this dangerous vortex hundreds of little Mr. Busk's paper mentions Siebold's original view of the monads, with other small fry, fall victims to the de- vegetable nature of the Volvox, and says:—“ Ehrenberg's vouring teeth and jaws of this fell tyrant of the stagnant errors in the case of the Volvox, are not those of direct obpool. But how, it may be asked, how is this vortex servation, but in this instance, as in very many others, it produced? If the cilia have this downward and upward is obvious that Ehrenberg has allowed his imagination, motion, we should conclude that the water will only be working upon preconceived notions, to play the part of disturbed without producing a current in one direction. reason in the interpretation of correctly observed phenoProfessor Quekett's explanation of this phenomenon is so mena; he has thence, in the explanation of what he has clear and satisfactory that I cannot do better than quote seen correctly, fallen into great and important errors." his own words, from a paper read before the Microsco-"While the recent progress of knowledge," he sayspical Society, in April, 1845, "On the Ciliary Movement with respect to the lowest classes of organised beings, in the Gill-ray of the Common Mussel (Mytilus edulis)." | places an observer of the present day in a position so He says, "If one of the rays be placed under the micro-much more advantageous, that it is scarcely fair to institute scope with the large cilia uppermost, when the movement a comparison between Professor Williamson and the is nearly stopped each cilium will be found to present, besides the usual curved motion in a vertical plane, another, although slight, yet important movement on itself, in a direction nearly at right angles to the preceding, which movement occupies just one-quarter of a circle, and is precisely analogous to that of the quills in the wings of birds during their flight, or to what we are more familiar with, namely, the feathering of an oar in rowing. The problem can be easily solved by allowing that the cilia are broader in one direction than in the other, and by giving to each of them a motion similar to the feathering of an oar, before alluded to, and which we find to be really the case. To see this feathering movement in the most satisfactory manner, the cilia must have become nearly quiescent; and if that portion which is attached to the gill-ray, and which may be termed the root, be carefully examined, it will be found to make a circular movement, whilst the filament itself is being bent upwards or downwards, the cilia also become alternately light and dark, in consequence of their being of a flattened figure, and the circular movement causes them to present at one time the broad surface, and at another the edge. The root of each cilium is of a globular figure, and Elirenberg supposes that minute muscles are attached to this part, which gives to it all its motions."
The great improvements that have been made in the microscope of late years show the physiologist that there is scarcely an animal throughout the various classes, both vertebrate and invertebrate, in which these cilia do not exist in some way or other. The motion is either voluntary or involuntary, according to the nature of the functions they have to perform. They are also placed in a variety of ways in different subjects-in some they are confined to the edges, in others to some part of the internal organs. In the rotifer vulgaris, as we have seen, they form two circular rows; in others of this class there is only one wreath of cilia round the mouth, as in the stentor and notommata parisita; others, again, have seven or eight of these wreaths.
I have only space for one more specimen; in this the cilia are distributed over the whole surface of the body, and, as far as I am aware, it is almost the only instance in which they are so placed. I allude to the volvox globator, a very beautiful microscopic object, which has engaged the time and talents of eminent men, in endeavouring to determine whether it belongs to the animal or vegetable kingdom.
In the Microscopic Transactions for January 1853, two papers are published on the structure of the Volvox; one by
great laborious Prussian microscopist at the time his works were written, still it is much to be regretted that these modern lights, clear as they are, have not apparently been allowed to penetrate his mind, and that one to whom science is so much and so deeply indebted should retain views long since deservedly exploded by nearly all competent observers."
Mr. Busk's paper then goes on to describe the form and structure of the volvox, in which description, though in general very correct, there is an error in describing it as a sphere. My own often repeated observations have convinced me that the mature volvox is not a sphere, being slightly elongated, and larger at one end than the other. Nor is this error in Professor Williamson's and Mr. Busk's description an unimportant one, since the peculiar form of the volvox is connected with other circumstances attending it, which have been entirely omitted by those gentlemen, as I shall show further on. The grounds on which the vegetable nature of the Volvox is maintained are, 1st. That chemical reagents act upon it nearly in the same way as upon starch, which is purely a vegetable production. 2ndly. That the cells and their contents are similar in structure to those in many of the Algo. That these, however, are very doubtful proofs, will, I think appear, from the fact that another substance, called cellulose, is acted on by the same chemical re-agents that change the colour of starch, and is affected nearly in the same way. Now it appears that cellulose exists, not only in vege table substances, but it is found in many animals, and even in the brain and spinal cord of man. In the Quarterly Journal of Microscopical Science, No. 6, January, 1854, is a paper on this subject by R. Virchow, in which he says-"We are acquainted with a series of varieties of vegetable cellulose, but the substance now in question appears to be distinguished above all by its slight power of resistance to re-agents, seeing that concentrated acids and alkalies attack it more powerfully than is usually the case with the cellulose of plants." Virchow's experiments and observations have been verified by Mr. Busk himself, who, in the course of his paper says, "the corpuscles were starch and not cellulose, and possessed all the structural, chemical, and optical properties of starch, as it occurs in plants."
It appears that Carl Schmidt was the first to discover the presence of cellulose in the ascidians, (a genus of moluscous animals without shells); it was previously only known to exist in plants, but he showed that it was also a constituent of the animal tissue, and the researches of
Kolliker, Lowig, Schacht, and Huxley have established this important fact. Schacht says, "In the mantle of the ascidians there is a substance insoluble in caustic potass, but soluble in sulphuric acid, which is turned a beautiful blue by iodine and sulphuric acid, and which consequently consists entirely of cellulose." The chemical relation of the cellulose itself, however, in the ascidians examined by me, is not essentially different from vegetable cellulose. Caustic potass has no effect upon either; sulphuric acid dissolves both, iodine and sulphuric acid colour both equally blue. Even Siebold says: "I must here remark, that we can scarcely expect chemistry to decide what is animal and what plant, having several times been deceived in our hopes in this respect. The non-nitrogenous cellulose, which at first sight appears to be an exclusive attribute of the vegetable, also occurs pretty generally disseminated in the animal kingdom." Here then, there seems to be an answer to the conclusion that the volvox must be of a vegetable nature because the colour is changed by chemical re-agents.
Siebold then launches his inky thunderbolt against Ehrenberg, accusing him with obstinately adhering to the chain of delusions and errors in which he has more and more closely involved himself from year to year. Then, by way of, "a Roland for an Oliver," in return for the sarcasm on the double-bodied wonder, he commences an attack on Ehrenberg's multiform animalcule, depriving it of all the poetry of its existence by degrading it to the rank of a mere vegetable!
I have kept them in tumbler glasses for as long as four or five months in the summer, and then, from some cause or other, although no change in their treatment had taken place, they languish, sink to the bottom, die, and decompose; a dirty, brownish sediment is ali that remains of them, not a trace being left of what they once were. I have never seen any approach to the " hybernating state," the "winter spores," mentioned by Mr. Busk, but I shall now look out for them. I have proposed to myself a mode of examination which I have not yet tried. It is very desirable to be convinced one way or the other, but "who shall decide when Doctors disagree?" I have said that the mature Volvox is not a sphere, as described in the papers before mentioned, and that there are some circumstances attending this creature which have been entirely omitted in those papers. I will now endeavour to describe what I have myself so often observed. The mature volvox, though of a globular form, is not a perfect sphere, being slightly elongated, and larger near one end than the other. Round the interior of this larger end the young volvoces are arranged; they are not promiscuously placed all over the internal surface. The creature always revolves on the long axis, and progresses with the small end foremost, the revolution being at right angles with the onward movement. When at rest the current in the water may be seen flowing from the small end, down the sides over the whole surface of the transparent globe. This current is no doubt produced by the vibrations of the cilia, as in the rotifer before described, only in this case they are distributed all over the surface, each green gemmule, or zoospore, or animalcule, having two cilia, as described by all parties, however they may differ in other respects, When they are quiescent is the time for observing not only the cilia but the connecting threads or tubes. Of these there are usually six, proceeding from the periphery of each green gemmule to as many of its next neighbours, forming a beautifully bright hyaline network all over the surface, or within a very small depth of it. These threads are said by Professor Williamson and Mr. Busk to be sometimes double, and even triple, but I am inclined to think this is an optical illusion. It is difficult to see them at all, but, under favourable circumstances, they appear like extremely fine transparent tubes; these may easily appear to be double. If we hold up a thin glass tube between our eye and the light, we shall see two lines, because we look through a greater thickness of glass at the sides than in the middle, where the rays can pass directly through. In some positions we may see three lines, or only one, according to the direction in which the light impinges upon the tube, and as these tubes lie in all directions in the volvox, the deception may easily take place.
With respect to the second proof of its vegetable nature, namely, the close relationship between the cellular appearance of the volvox and that of algae and confervæ, it would seem to have as little weight as the former. The great similarity of vegetable and animal tissues in their early stages of development, is now well known to the physiologist. Even Professor Williamson says, "It is only whilst the segmentation of the gemmæ is in progress, that a real relation exists between volvox and young growing confervæ." Even the identity of the two is adVocated. Schultze has a paper "On the identity of the colouring matter present in several animals, with the chlorophyll of plants," and Huxley has another, "On the identity of structure of plants and animals," (both published in the "Quarterly Journal of the Microscopical Society," for July, 1853,) in which, after some technical explanations, he says:- Upon this view we find that all the discrepancies which had appeared to exist between the animal and vegetable substances disappear, and it becomes easy to trace the absolute identity of plan in the two, the differences between them being produced merely by the nature and form of the deposits in, or modifications of, the periplastic substance." From these quotations we may see how much difficulty there is in determining where Of the red spots in the zoospores (or animalcules, as the line should be drawn between the animal and disputants may please to call them) there are several vegetable kingdoms. Mr. Huxley, the gentleman opinions-Ehrenberg calls them "red eyes." The vege last quoted, appears to indulge a little in the table advocates will not allow them to be eyes. Yet Mr. 'pleasures of imagination," as Ehrenberg has before Busk, who calls them brown spots, says, "They all been said to do. He observes, "The plant, then, is appear to look the same way"-that is, the spots are an animal confined in a wooden case, and Nature, placed in a corresponding situation in all the cells, on like Sycorax, holds thousands of "delicate ariels" im- one side, near the narrow end; and this description prisoned within every oak. She is jealous of letting us agrees with the figure given by Ehrenberg. They are know this, and, among the higher and more conspicuous also placed in that way in Professor Williamson's figures. forms of plants, reveals it only by such obscure manifesta- It might be a curious point to ascertain if the revolving tions as the shrinking of the sensitive plant, the sudden motion is toward the side that the eyes appear to look. clasp of the dionæa, or, still more slightly, by the pheno- According to Siebold, Nägeli says they are "red oil mena of the cyclosis. But among the immense variety of drops." But whatever these spots may be, they exist creatures which belong to the invisible world, she allows in many animals; in the rotifera, and many others; the her dryads more liberty, and the protococci, the volvox, wheel-animalcule has the red spot; and Mr. Gosse, in and, indeed, all the algae, are, during one period of their describing a parasite of this class which he found living existence, as animals of a like grade in the scale. True, within the volvox, and devouring the young ones, says― they are doomed to shut themselves up in their wooden"The usual occipital sac carries a large eye, of a rich cages, and remain quiescent, but in this respect they are no worse off than the polype, or the oyster, even. Now, this may be all very fine, but of the voivoces not "shut themselves up in their wooden cages." They live and flourish, for a time, in all their beauty.
There is also in these green gems a circular clear space, which has a contractile property, described by Mr. Busk as being " very regularly rythmical, the contractions or pulsations occurring at intervals of 38 to 41
seconds, and in some cases longer. It takes place suddenly, and amounts to a complete obliteration of the cavity, or vaccuole, whilst the dilatation is slow and gradual." Mr. Busk says this contractility is "a property already known to be possessed by similar spaces or vacuoles in vegetable spores." He should also have said itexists in the animal. Mr. Gosse describes it in the para, site before-mentioned (the Notommata parasita); but he seems determined to class this beautifully organised, active, and apparently living object, along with many others as active, with the vegetable algae and confervæ. However this may be, it is no more extraordinary that a multitude of animalcules should be located at regular distances upon a world of their own, in a shape of a transparent globular membrane, having threads or tubes of communication, which, for ought we know, may possibly perform the same office to them that our telegraph wires do to us: I say this would be no more extraordinary than the dwellings of the zoophite. In this little tree, with its numerous branches, growing from one small stem affixed to a rock, or an oyster shell perhaps, at the bottom of the sea,-every branch is a double row of houses, built up back to back with the greatest regularity, each house having a living inhabitant, of which there are many hundreds in this small compass. These minute animals form their dwellings without line, compass, or square, and yet no builder amongst us can arrange his brick and mortar houses in more beautiful order.
With respect to the Volvox, it seems a pity to part with it as a vegetable. It would be the most agreeable side of the question to join in Ehrenberg's pleasures of imagination, and fancy those red spots to be eyes. It is admitted that they all look one way." These vegetables certainly appear to exhibit some signs of vitality. I have never seen them come in direct collision, so as to stop each other when careering in opposite directions; they always glide by very gently. Perhaps the whirlpool which they make in the water gives them notice of each other's proximity. After being at rest for a time, they will suddenly start off and re-commence their revolving and progressive motion through the water. Sometimes two or three may be seen in company, revolving slowly near the same spot for a while; and when congregated near the surface, or on the side of the glass next the light, if the water be slightly disturbed with the tip of the finger or a small pencil stick, they will all sink down to the bottom, as if alarmed. When the water is no longer agitated, they soon resume their previous position.
When the young volvoces are fully developed, they become detached from the inner surface of the parent globe, and revolve freely for a time, another generation may then be seen within these young ones. At length the parent globe bursts, and the young ones roll out and commence their independent life; increasing in size and maturity, until they become like the parent.
I have also had more than one opportunity of seeing the fractured and empty globe revolve through the water as before, for several days after the young had left it, although the edges of the fractured globe appeared ragged, and the globular form partly collapsed. One singular circumstance I have to notice. On one occasion, I had not looked at the volvoces for several days; when I returned I was surprised to find most of the old forms had disappeared, and a new race, apparently a new species, were very actively enjoying their young existence, much smaller than those I had left there, but with larger zoospores and a much thicker hy aline envelope. There apparently some mystery about these beings, which is not yet understood. I am not at all surprised at Ehrenberg's "imagination," when I behold these wonderful creatures, orb within orb, "instinct with life" in in every part, rolling onward in beauty and magnificence, beyond conception to any one who has not beheld them, unceasingly revolving their brilliant, emerald forms in sportive grandeur; while the deep rubies that their eyes seem made of complete the splendour of their gorgeous
bodies, a world of separate beings united in one bright globe, apparently animated by one soul, that conducts the shining mass at pleasure, as fancy or occasion leads. The wondrous structure of those splendid beings, with myriads of other minute and beautiful organisms which the microscope has made us acquainted with, may well overwhelm a contemplative mind with astonishment and fervent adoration of that Great Power whose infinite wisdom and goodness shines forth with equal lustre in these as in the greatest and most glorious works of the boundless universe.
Mr. C. VARLEY said that, in contributing two microscopes to illustrate some of the facts stated by Mr. Leonard, he might observe that they had both been honoured by the Society's Medals. The vial microscope was for continuous observations of plants and animalcules growing therein. The other had a lever movement, for the stage, by which any one object or animalcule, amongst many others, might be kept continually in sight, and all its evolutions observed. This was particularly the case with the volvox globator, which, being a shell, with younger globes within it, and those with a third set becoming visible in them, had raised the question whether they were animals or plants, the shell suggesting the idea of a seed-vessel. Transversely they were perfect globes, but longitudinally the hinder part had a tendency towards a point, though not so much as an egg. This hinder part opened, and the young globes (which, when there was room, were rotating within the larger) swam out and rotated. From his experience he could say decidedly that they were animals, and not plants. He could find nothing that bore any analogy to plants; but, instead of being one animal, it appeared to be a family which grew together in one globular shell. There were many examples of animal families; the bell polypus, numbering from one to one hundred, might frequently be seen all growing together like a tree, an animal at the end of each branch. The gonium pectoralia grew together in sixteens. The discovery made by aid of the microscope, that the sap of plants circulated, and that that motion was their life, had shown that plants bore a much closer analogy to animals than was usually imagined. But this fact brought with it a marked and beautiful distinction; animals had arteries and veins, plants had not. The circulation in animals was one whole or united stream from end to end, all the ramifications being open to one another in various directions. In plants itwas not so. Plants were composed of cells of variable proportions, in each of which the sap circulated up one side and down the other; each cell was capable of living alone for several days, when separated from all the others, there being no opening or passage from any one cell to another; therefore a plant was a family of living cells, too numerous to be stated by numbers-a family, as it were, of individual lives. Often a very small part of a plant would send out roots and become complete, thus proving that it contained all the principles of life, complete in itself, independent of the plant from which it was taken. When by the microscope we observed the extraordinary delicacy of the cells of plants, the wonder was how they could even bear the wind. This brought to light an important fact, a natural arrangement, which gave security under very rough usage; most of the cells might be compared with a quill, being about that proportion of thickness to the space within. This space contained a most delicate lining, which did not adhere to the outer case, and this delicate sac was filled with two fluids. This was a new fact, and a more marked difference between vegetable and animal circulation. The proper circulating fluid adhered to the lining, and flowed or slid up one half of the tube, over the end and down the other half, again to rise. There was no wall or division between the rising and falling currents to support or separate them, but the central space was filled by a fluid