136 



CHAPTERS ON EVOLUTION. 



find the malleus to be of large size, and to be divided so that one part 

 (B, m) becomes transformed into the " quadrate bone," and another 

 (B, m l ) into the upper part of the lower jaw (/) itself. In the fish a 

 third bone (c, m") may actually appear in connection with the lower 

 jaw (/), and as the result of the division of the part representing the 

 " malleus " of Man and quadrupeds. So that, divesting the subject 

 of all technicality, we may say that, as we first enter the vertebrate 

 sub-kingdom, we find the " malleus " to be represented in the fishes 

 by no less than three bones (c, m, m', m") which are connected 

 with the upper part of the lower jaw and lie outside the ear altogether. 

 Next, in the reptile and bird we find a modification of this arrange- 

 ment to hold good. Here the malleus is divided into two portions 

 (m, m } ) only; these parts, however, being still concerned in the 

 articulation of the lower jaw (/). But in Man and his neighbour- 

 quadrupeds (A), these outside bones become pushed upwards in the 

 course of development, and are finally enclosed within the skull. They 

 thus appear as the "malleus" of the ear (A, m), having no connection 

 with the jaw, and being concerned in the higher function of conveying 

 impressions of sound to the internal ear. The upper part of the lower 

 jaw of the lower vertebrate is in fact taken into the interior of the 

 skull and ear, when we reach the quadruped class. The two com- 

 panion bones (A, c, i) of the malleus in the ear, likewise represent separate 

 parts of the skull, which in higher life become modified for the 

 hearing function. And a glance at the accompanying diagram will 

 serve to show how the other bones "incus" (/) and 

 "stapes" (c) of the quadruped ear are represented 

 wholly or in part in lower life, and how they attain 

 their higher place and function simply as the result 

 of modification, and of the evolution of a new structure 

 from the materials of an already existing type. Such 

 modification is simply part of the wider process we 

 see everywhere illustrated in animal life at large, 

 whereby complication and diversity of structure and 

 form are the results of no new creations, but of the 

 development, the splitting up, and differentiation of 

 already existing parts. 



So is it also, with plants in some of their most 

 unusual aspects. The strange features in animals 

 and plants are in reality but the altered " common- 

 place of nature." By way of illustration, the subject 

 of the threadlike " tendrils " of plants presents itself 

 m a prominent manner. It would be hard to discover any organs of 

 plants which are better known than these. Poetic allegory itself has 

 ever found in the simile of the " tendrils," the best guise under which 

 the affections of mankind might be shadowed forth ; and that weak- 



62. A LEAF 

 AND ITS PARTS. 



