as some botanists tell us, in place of the end of the leaf stalk also. We find a very simple modification to be

thus represented; certain parts of a leaf become altered to enable the plant to climb. Tendrils here are homologous with leaflets. In the lentil it is the leafstalk itself which is long drawn out to form the climbing thread. The vine (Fig. 8) or passion flower may be selected as our next example. Here the tendrils appear to be formed in a very different fashion from that seen in the pea. parently the tendril (tt) in the vine and passion flower is a modified branch; such

Ap

Fig. 8. TENDRIL OF A VINE.

The Vir

an opinion being arrived at from a study of the relations of the tendril to the stem and normal branches of the plant. ginia Creeper likewise climbs by means of its altered. tendril-like branches. Once again we meet with a similar end-that of forming a climbing supportserved by a different means, when we turn to the Smilax (Fig. 9), which in Southern Europe replaces the Bryony of our English hedgerows. The leaves of Smilax are heart-shaped, and when we look at the points at which the leaves spring from the stem, we Fig. 9. SMILAX. detect two tendrils (tt), which pass to the surrounding plants there to entwine themselves in complex fashion. Now, what are the tendrils of Smilax? Our knowledge of the leaf and our observation of the position of our tendrils enable us to answer the question. What organs arise from the base of the leaf stalk? The reply, illustrated by a reference to Fig. 6, is "stipules" (ss); and stipules are paired organs. Therefore, we conclude that the tendrils of Smilax are simply altered stipules. The Yellow Vetch (Fig. 10), which adorns our cornfields, reverses the conditions of Smilax. The stipules (ss) remain in the Vetch to represent the leaves, whilst the leaf stalk itself and its leaflets become altered as in the Pea, only to a greater degree, to enable Lathyrus to indulge its climbing propensities. Thus does a study of tendrils illustrate in apt fashion the bearings of homology. But for this science of

Fig. 10. YELLOW VETCH.

likenesses we should not be enabled to unravel some of the complexities which beset the study of how a plant climbs; and we again note how modification and adaptation, as distinguished from new creations, form the way of the world of life.

No less interesting in certain of its aspects is the study of the "thorns" and "prickles" which "set the rosebud," or give to the hawthorn its characteristic name and feature. The popular botany of every-day life is content to consider prickles and thorns to represent one and the same kind of structure. But the science of likenesses is care

You will note that from the thorns (a a) leaves spring, and in this observation lies the key to the understanding of their relationship with other parts of the plant. Leaves are only borne on the stem itself or on the appendages of the stem we familiarly call branches. Therefore the presence of leaves on the thorns plainly tells us that these appendages of Sloe and Hawthorn are in reality stunted branches. Nor are we left in the slightest doubt as to the nature of these objects; for many of the plants which in a wild state possess thorns alone produce full-grown branches under cultivation. "Spinosæ arbores cultura sæpius deponunt spinas in hortis," said Linnæus, and the Sloe itself illustrates the remark. But the prickles of the Rose (Fig. 11, B), which might readily be deemed thorns in miniature, now demand attention. The prickle has no intimate connection with the stem. On the contrary, it is merely a hardened appendage of the skin of the stem or leaf as the case may be. A prickle causes no trouble in its detachment from the stem, and the botanist would inform us that these appendages in their true nature correspond to hardened hairs. Lastly, we may meet with double prickles, or spines, which spring from the axils of leaves and from the base of the leaf stalk. In the Acacias and the American Prickly Ash (Echinopanax) we may see spines the origin of which is not hard to trace, and which spring from the bases of the leaves. Just as

the tendrils of the Smilax were formed from "stipules," so we perceive in the Acacias how these latter organs may be altered to form the "spines," or "prickles," of these plants.

Passing from leaves and flowers to fruits, we enter a new but equally interesting field of speculation with the last. Let us firstly inquire what is the nature of the structure to which the botanist gives the name of "fruit." It is perfectly evident from the common knowledge of Nature's processes which ordinary observation affords that the fruit is merely part of the flower. The buds of springtime and the blossoms of summer must precede the fruit of the autumn ; and the promise of "a golden reaping" is heralded by the early growth of the vernal season. Without the flower, then, the fruit would be non-existent, and considering that within the vast majority of fruits we find the seeds, we can readily construct a definition of the botanical fruit by defining it as "the ripe pistil." Such is the invariable nature of the fruit in the mind of the botanist. Popularly, however, "fruits" are only to be so called when they are edible. The mental and scientific concept of the man of science vanishes before the practical matter-of-fact definition of a fruit as "that which is good to eat "; and perhaps each definition meets in its own way the exigencies and circumstances which called it forth.

But the study of fruits from the botanical side presents us with a highly interesting illustration of the value of "homology," as showing us how the modification of simple and well-known parts of the flower may become transformed so as to be wellnigh unrecognisable in the fruit. No better illustration of the latter fact can be found than in the Strawberries (Fig. 12), which secured the full admiration of Dr. Boteler, who declared that "Doubtless God could have made a better berry, but doubtless God never did "-a remark the correctness of which

will probably be viewed proportionately by the Fig. 12. STRAWBERRY. individual minds and tastes which may consider the saying. Glancing at the Strawberry flower, we see no promise therein of the toothsome fruit which the summer brings; and we may well be puzzled to discover the true nature of our berry, even after a close examination of its substance. The apple cut across is seen to contain seed-therefore we may reasonably enough imagine that, whatever growth has subsequently occurred to the apple blossom, we find the seed-producing pistil of the flower to be represented in its interior. But no seeds are to be found in the interior of Dr. Boteler's berry. is the true fruit-the ripened pistil—of the Strawberry, and what is

Where, then,

the nature of the succulent mass we eat? The science of likenesses answers the question by a reference to the growth of the Strawberry itself. In the flower, the pistil is seen to be composed of a great many little parts, called "carpels." As the flower fades and the pistil ripens, the end of the flower-stalk (called in botany the receptacle) begins to swell out and to exceed the rest of the flower in its growth. Soon it becomes red and succulent, and the little green carpels of the pistil, each containing a single seed, come in due time to be separated from each other, and to be embedded in the juicy mass on which, when it was the simple end of the flower-stalk, it was set. Thus to offer a friend the "botanical fruit" of the Strawberry would be a proceeding tantamount to invite him to a Barmecide's feast: since, to fulfil the promise, we should simply require to pick out from the surface of the berry the little green carpels which represent the ripe pistil of the flower-the popular "fruit," as we have seen, being merely the enlarged end of the flowerstalk. In such a case, one might well be excused for preferring the common construction of the term "fruit" to the scientific, and for neglecting the intellectual aspect of the berry in favour of the exercise of practical æsthetics as applied to the end of the flower-stalk.

The Strawberry does not stand alone in its illustration of the curious facts concerning the transformation of flowers which the study

of homologies elicits. What, for example, is to be said of the Rose-fruit (Fig. 13) itself, save that the familiar red "hip" of our hedgerows is formed by the enlarged and hollowed flower-stalk (c), along with the calyx (s) or outer part of the flower; or, according to some botanists, by the calyx alone, whose green leaves become thickened, red, and glistening as the summer passes into the autumn, and come to enclose the true fruit (fr) in the form of the little carpels similar in nature to those on the outside of the Strawberry. So that the Fig. 13. ROSE FRUIT. difference between the "hip" of the Rose and the Strawberry simply consists in the fact that the Rose flower-stalk is hollow and has the fruits inside, whilst the end of the Strawberry flowerstalk is solid, and has its fruits outside. The Apple and Pear likewise exhibit much the same arrangement as the Rose and Strawberry in respect of their fruits. If we suppose the hip of the Rose to have its walls extremely thickened and fleshy, we should convert it into a form of fruit resembling the Apple or Pear. No less interesting is the nature of the Fig, which, to be properly understood, should

be examined as it grows in the hothouse. Slice your fig longwise (Fig. 14 a), and you will see in its interior, not seeds, but " flowers"; some with stamens (b) alone, others (c) with pistils alone. The Fig appears before us as another example of the hollowing of the flower-stalk, with this important difference, that not merely the fruits but the flowers are contained in its interior.

It only remains for us to sum up the results and general conclusions to which our brief study of the science of likenesses may be said legitimately to lead us. Turning

firstly to the features we have just been discussing, we have noted, for instance, that the leaf was the type of the whole plant, and that as the leaf became modified to form the "flower," so that flower and its parts, still representing leaves, became further altered to form the "fruit" under all its varied aspects and forms. From a simple structure-the leaf-we thus discover, by the aid of the science of likenesses, complex and elaborate organs and parts to be developed. What lesson do such examples teach us concerning the order of Nature at large? Do these lessons argue in favour of evolution or against that theory of Nature? The answer is not for a single moment doubtful. If, as our inquiry shows, it is the way of Nature to produce many and varied structures by the modification of one simple organ or part, surely there is no greater wonder involved in the idea, that by the same process of development she has woven from simple forms the whole complex warp and woof of the living world. When we see Nature in her abnormal methods of development revealing to us, under the guise of her sports and freaks amidst the flowers, the true composition of the pistil and stamens, or altering the same structure to form the varied fruits; when we discover that the complex skull has apparently been built up through slow and gradual modifications from skulls of simpler type, which vanish away, in the lowest confines of the vertebrate animals, in the barely defined skulless "cord" of the lowest fish, we may not esteem it an impossibility that all organic forms have been evolved under like conditions of development.

Nor must we omit to think of another important point involved. in the study of homologies. If Nature is, as we have shown, liable to modify and alter continually the work of her hands, can such a practice be held to favour the origin of new species by the way which evolution points out? When the flower returns to