gine, however subtly devised, can evade this law of equivalence, or perform on its own account the smallest modicum of work.'

The learned writer then proceeds to inquire if the animal body is to be classed among machines. In ascending a mountain, lifting a weight, or throwing a stone, we are conscious of exerting force; and every such exertion is proved to be attended by a perfectly definite consumption of fuel (say carbon) in the muscles, which performs just as much work as its combustion out of the body would effect. The identity of this mode of action with that of a steam

engine or a galvanic battery is then. sought to be proved, on the ground that here also (H+W) is a constant quantity. As this is the very core of the argument, and that to which I propose to apply the testing question, 'Is it true?' I will not run any risk of misrepresenting it by any attempt at condensation, but will give it in extenso, in the very words of the author :

Let us look to the antecedents of this force. We derive the muscle and fat of our bodies from what we eat. Animal heat you know to be due to the slow combustion of this fuel. My arm is now inactive, and the ordinary slow combustion of my blood and tissue is going on. For every grain of fuel thus burnt a perfectly definite amount of heat has been produced. I now contract my biceps muscle without causing it to perform external work. The combustion is quickened and the heat is increased, this additional heat being liberated in the muscle itself. I lay hold of a fifty-six pound weight, and by the contraction of my biceps lift it through the vertical space of a foot. The blood and tissues consumed during this contraction have not developed in the muscle their due amount of heat. A quantity of heat is at this moment missing in my muscle which would raise the temperature of an ounce of water somewhat more than one degree Fahrenheit. I liberate the weight; it falls to the earth, and by its collision generates the precise amount of heat missing in the muscle. My muscular heat is thus transferred from its local hearth to external space. The fuel is consumed in my body, but the heat of combustion is produced outside my body. The case is substantially the same as that of the voltaic battery when it performs external work or produces external heat. All this points to the conclusion that the force we employ in muscular exertion is the force of burning fuel and not of creative will. In the light of these facts the body is seen to be as incapable of generating energy without expenditure as the solids and liquids of the voltaic battery. The body, in other words, falls into

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the category of machines. We can do with the body all that we have already done with the battery-heat platinum wires, decompose water, magnetise iron, and deflect a magnetic needle. The combustion of muscle may be made to produce all these effects, as the combustion of zinc may be caused to produce them. By turning the handle of a magnetoelectric machine, a coil of wire may be caused to rotate between the poles of a magnet. As long as the two ends of the coil are unconnected we have simply to overcome the ordinary inertia and friction of the machine in ends of the coil are united by a thin platinum turning the handle. But the moment the two wire a sudden addition of labor is thrown upon the turning arm. When the necessary labor is expended its equivalent immediately appears. The platinum wire glows. can readily maintain it at a white heat or even fuse it. This is a very remarkable result. From the muscles of the arm, with a temperature of 100 degrees, we extract the temperature of molten platinum, which is many thousand degrees. The miracle here is the reverse of that of the burning bush mentioned in Genesis. There the bush burned but was not consumed, here the blood is consumed but does not burn. The similarity of the action with that of the voltaic battery when it heats an external wire is too obvious to need pointing out. When the machine is used to des compose water, the heat of the muscle, like that of the battery, is consumed in molecular work, being fully restored when the gases recombine. As before, also, the transmuted heat of the muscles may be bottled up, carried to the polar regions, and there restored to its pristine form. The matter of the human body is the same as that of the world around us, and here we find the forces of the human body identical with those of inorganic nature.*

When in a certain kind of evening entertainment we have our watch taken

from our pocket, beaten to atoms in a mortar, fired from a pistol, and otherwise maltreated, we know that it will in some way or other be restored to us, sound and perfect as before, perhaps from the middle of a yesterday's loaf, perhaps cut from the centre of a fruit grown to maturity on the table before our eyes. All this, however, is the very A B C of conjuring, compared with this effort of modern science, which bottles up the heat from our biceps and other muscles, carries it off to the North Pole or elsewhere, to be fully restored' when the gases are exploded. We must confess this is no laughing matter either for the muscle or for the moral consequences involved in the transference.'

vellous statement I would premise one observation. I do not concede that the whole train of argument even touches the essence of the question of automatism. I hold that even were all the facts here stated fully established, the question of origination of action would be left in precisely the same position as before. But I am content, for the sake of the argument, to assume it to be otherwise, and to allow that the scientific statements here (and elsewhere) made are not only necessary, but adequate, for the demonstration of man's clock-like nature; and as such, I propose to inquire how far they are founded upon science, or how far they come under the head of flights of fancy.

The answer is so very simple that I hesitate somewhat to give it, lest its very plainness, in reply to so lengthy and so eloquent an elaboration, should cause its immediate rejection without consideration; as it is very much the custom in these latter days to accept science rather on authority than on investigation. Nevertheless, whatever may be the case in ethics, it is generally allowed that in exact science there is some absolute standard of truth, independent of the source whence it emanates. Encouraged by this consideration, and with a full consciousness and recognition of the importance of all the work that has been done in illustration of this question, I venture to assert that the whole force of the lengthy quotation above given is destroyed by the fact of its being in direct contradiction to the well-known and established facts of science-a contradiction as absolute and astounding as it is inexplicable.

From this sweeping verdict I wish only to except one position. No one would for a moment suppose that animal muscle performs mechanical work without what may be called consumption of fuel. This is one of the most familiar facts in physiology; and this consumption would necessarily be the same on any hypothesis of action, whether automatic or free volitional. Beyond this, I do not hesitate to say that the facts or statements above quoted are evolutions of individual consciousness rather than representations of nature.

Professor Tyndall states that when the contraction of the muscle performs ex

ternal work, the blood and tissue consumed have not developed in

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the muscle their due amount of heat. quantity of heat is missing, &c.' I can only say in reply to this, what physiologists very well know, that

THERE IS NO HEAT WHATEVER MISSING, and that the fuel consumed has here, as elsewhere, developed the due amount of heat. It is in this particular that animal tissue differs essentially from all machinery; and the difference is fundamental and conclusive. There is no transference of the muscular heat from its local hearth to external space.' Such a transference may easily be seen in any case to be impossible. Where the fuel burns, there the heat is given out. There is no such reversal as stated of the miracle of the burning bush-the body is consumed, and burns. consumed, and burns. The incandescence of the platinum wire neither is, nor can possibly be, the equivalent' of the heat missing' (which is in no sense whatever missing) from the muscle; and we cannot by any process obtain a temperature of many thousand degrees' from the temperature of the muscle, which is something below 100°. And it follows naturally that we cannot bottle up heat, which is not missing, and carry it to the North Pole, to be restored there by explosion and recombination of the gases.

If what I here assert be true, it is evident that the human muscle differs essentially from all machines, properly so called, and that any theory of animal automatism founded upon imaginary analogies between them utterly breaks down. All machines develop more or less internal heat, according as they perform less or more external work: (H+W) is a constant quantity. constant quantity. With muscle it is not so; the more external work is done, the more heat is developed in the muscle: (HW) is therefore not a constant quantity, but, in mathematical language, it is a direct function of the variable W. As W increases, so does H, although not in an absolutely constant degree; for after a certain amount of work has been done, any increase in it is attended by a somewhat greater ratio of increase in H.

Supposing that I am able to establish this position, which I have set forth with as much directness as possible, the result would be that the Equivalence of Force attack upon anthropomorphism

has experienced as disastrous a check as did formerly the Protoplasm column. But it will naturally be expected that the demonstration shall be complete, and shall not rest upon mere assertion. I propose, therefore, very briefly to sketch what has been done by physiologists, and to note the results of their inquiries into the relation between muscular work and heat.

It has often been a favorite pursuit of physiologists to attempt to demonstrate the analogy between muscular work and that of a steam-engine. Béclard, many years ago, made this attempt, and thought he had observed that less heat was developed in a muscle when it performed external work, than when it contracted without doing so, even against resistance. His experiments, however, were exceedingly rough, being performed with ordinary mercurial thermometers, and without any sufficient precautions against error. The thermo-pile as a means of research was unknown to him, and he himself was dissatisfied with his results. He even proposed a series of crucial tests, but did not carry them out into practice. Later Dr. Solger, made some investigations in the same direction with more refined apparatus and method. He even detected, as he supposed, some exceed ingly momentary fall of temperature of the muscle at the instant of contraction, which was, however, immediately followed by a rise. Mayerstein and Thiry followed on the same lines of experiment with doubtful results, but on the whole confirming Solger's observations. These observations are now merely of historical interest, as the more accurate investigations of late years have demonstrated that these somewhat anomalous results were due rather to physical errors in experiment than to physiological causes. It was shown in particular that the 'momentary cooling' was most probably a result of evaporation, as due allowance had not been made by any of the observers for this event.

*

* Hirn also attempted to draw some analogy between the development of heat in the steam-engine and that in muscle-only a matter of interest as recalling the verdict that was passed upon it by C. Voit :-' Die Bemühungen welche Hirn zu dem Zwecke anstellte, nachzuweisen, das die mechanische Leistungen des Organismus zu seiner Wärmeproduction in demselben Verhältnisse stehen, wie in

For the only thoroughly reliable researches into the quantitative relationssubsisting between muscular heat and work, we are indebted to Professor Heidenhain, of Breslau, whose experiments, carried on for a long period at the Physiological Institute, are models of care and exactitude. It would be out of place here to enter into any detailed account of his apparatus, and of his almost infinite precautions against error. I may say that the chief elements used were a very delicate reflecting galvanometer, a thermo-electric multiplier of bismuth and antimony, by means of which the most minute changes in temperature, to which the ordinary thermometer would be quite insensible, could be readily detected, and an elaborate contrivance for suspending the muscles and keeping them in equable contact with the thermo-pile, both during rest and during the ever-varying amounts of contraction. The contraction of the muscles was induced, of course, by the action of the electric current. The full account of his proceedings would occupy a volume. I must be content to give a brief résumé of the most important results.

Heidenhain experimented on muscle contracting freely without any weight or hindrance, on muscle exposed to stimulation, but prevented from contracting by being firmly attached to an immovable frame at each end, and on muscle allowed to contract freely, but lifting varying weights. Varied in every possible way, the general result was always the same.

Accompanying every action of muscle, there was an elevation of temperature; and this elevation was invariably greater when work was performed, than when the muscle contracted without doing work; it was also to a certain extent proportional to the amount of work done, but not always accurately so, as the phenomena varied according as the muscle was fresh in action or wearied after many contractions. In none of the many series of experiments, however, was there any departure from this general principle, that the more external work was done, the more internal heat was developed in the muscle.

der Dampfmaschine, sind aus mehrfachen Gründen als gescheitert zu betrachten.'

The latest conclusions of accurate science on this subject are very briefly sketched in Nature for September 20, 1877, and Heidenhain's experiments are thus alluded to :

The fact that in the living muscle heat always appears when the muscle does work (Heidenhain having shown that of two muscles equally weighted and undergoing equal contractions, one doing external work, while the other does none, the former gives out more heat than the latter), is an exception to the general rule in mechanics,, that heat disappears when work is done.

Thus, then, it is demonstrated that muscle is not merely mechanical in its action, and a fortiori that the animal of which it forms a part is not a machine. Its action is conditioned by forces, of the essential nature of which we know nothing, the correlative of which cannot be traced; and to say that these are the compounding of inorganic forces' is merely to clothe our utter ignorance of the nature of life in a form of words which will amuse the unphysiological ear, but which has no correspondence in thought or fact. All that has gone before is perfectly familiar ground to the physiologist; for those who care for further details I subjoin a few tables in a note.* But I would not leave this

* The following tables indicate several scries of observations on muscle contracting under various conditions of freedom, and lifting different weights. Each table consists of two columns. One, headed W., represents the amount of external work done, reduced to the centimeter-gramme scale; the other, headed T., indicates the proportional elevation of temperature, as marked in degrees of the arbitrary galvanometer scale. It will be remembered that the greatest elevation here indicated will be but a small fraction of one of our ordinary thermometer degrees.

branch of the subject without entering a formal protest against the unscientific idea of burning fuel on a local hearth,' and finding the resulting heat in 'external space.' Even to hint at the possibility of such a thing is to ignore all the plain facts and possibilities of physical science. When an external wire is heated by an electric current, the heat in the wire is not the heat which was generated by combustion of zinc in the battery. The heat appears where it is generated (in this as in all other cases), i.e. in the wire itself by its resistance to the free passage of the current, in something of the same way as heat is developed everywhere by resistance of motion-in other words, by friction. That there is a correspondence between the quantities in-. volved, depends upon the most obvious and well-known physical laws.

It is assumable that Professor Tyndall considered his entire argument, and all the scientific illustrations attached to it, to be solidary' as bearing upon this burning question' of man's free will; therefore, although I do not see the direct application of the following passage, I quote it as affording an opportunity for examining how much science has to say in the matter, and how much fancy :

And here we are able to solve an enigma which long perplexed scientific men, and which could not be solved until the bearing of the mechanical theory of heat upon the phenomena of the voltaic battery was understood. The puzzle was that a single cell could not decompose water. The reason is now plain enough. The solution of an equivalent of zinc in a single cell develops not much more than half the heat required to decompose an equivalent of water, and the single cell cannot cede an amount of force which it does not possess. But by forming a battery of two cells instead of one we develop an amount of heat slightly in excess of that needed for the decomposition of the water. The two-celled

results with the same muscle fatigued with its previous work. In the latter cases the elevations of temperature are not so uniform as in the former. Table I. may be read thus:When the muscle does no external work, but is caused to contract freely, the scale marks an elevation of temperature of 8.5°. When the work is represented by 20, the scale marks 12°, and when 40, the scale marks 14°. On relieving the muscle from all weight, the scale again marks 8.5°. The others are read in like manner. In all these observations the duration of the contraction in seconds was carefully allowed for.