TRANSACTIONS OF THE SECTIONS. 115 
faculties to foresee, invent, and adapt, we dimly conceive, in analogous but more 
perfect results, the exercise of like faculties in a transcendentally higher degree. 
To conceive the direct formation and adjustment of such an organization as that 
of the Chiromys to its purpose accords best with the mode of our finite human 
adaptive operations, but least with the sum of present observations bearing upon 
the origin of species. Such observations have led to the conception that the species 
of organisms may be due to natural laws or secondary causes, operating to produce 
them in orderly succession and progression*; and also to the suggestion of the 
mode of operation of such secondary causes. 
As a test of the value of some of these suggestions in making Inown or render- 
ing intelligible the origin of a species, the organization of the Aye-aye lends 
itself with peculiar force. 
Buffon, assuming that a certain number of species had been originally created 
after a manner analogous to, and conceivable by, the way in which human machines 
are made, conceived that there was a tendency in their offspring to degenerate from 
the original type; and he refers the Linnean species, about 200 in number, which 
are described in his great work, to about fifteen primitive stocks. As, however, 
the Aye-aye, had he known as much as is now known of it, might have been 
referred to a “ primitive type or stock,” or to one of the “isolated forms” such as 
Buffon conceived the Elephant and the Mole to be, the author proceeded to apply 
the Aye-aye, as a test, to Lamarck’s hypothesis of the origin of species. : 
The ‘Philosophie Zoologique’ teaches that species, like varieties, have their 
origin, maturity, and departure, changing with the course of the changing operation 
of the causes that produced them; that such so-induced changes of form and 
structure lead to changes in powers and actions, and that such actions become 
another cause of altered structure ; that the more frequent employment of certain 
parts or organs leads to a proportional increase in the development of such parts; 
and that as the increased exercise of one part is usually accompanied by a corre- 
sponding disuse of another part, this very disuse, by inducing a proportional degree 
of atrophy, becomes another element in the progressive mutation of organic forms f. 
According to the modifying influences suggested by Lamarck, a Lemurine qua- 
draped, attracted by the noise of a boring caterpillar in the hough on which it 
happened to be perched, instinctively applied its incisors to the bark, and, by fre- 
quent repetition of such efforts, increased the mass of the gnawing muscles, which, 
stimulating the growth of the bone, led to concomitant modifications in the size 
and proportion of the jaws. The incisors, by repeated pressure, either became 
welded into a single pair above and below—or, the stimulus to excessive growth 
being concentrated on one incisor, the neighbouring teeth became atrophied by 
disuse, and by derivation of their nutrient fluid to the contiguous pulp; hence the 
preponderating size of the pair of front teeth, and the extent of edentulous space 
behind them. Concomitantly with the efforts excited by the particular larvivorous 
tendency of a certain Madagascar Lemur to expose the canal in which its favourite 
morsel lay hidden, were repeated endeavours to poke the longest finger into the 
burrow so laid open. The repeated squeezing of the soft skin, with the compression 
of the nerves and vessels, permanently affected the growth of such digit, and kept 
it reduced to the blighted state, whereby it happens to be suited to the work of 
extracting the larva. Lamarck supposes all these changes to be gradual, and 
effected only through long succession of generations; he assumes that changes of 
structure, due to habitual efforts and actions, are transmissible to offspring ; and 
he finally invokes, like his successors, the requisite lapse of time and long course 
of generations. It is to be supposed that, until the modifications of dental and 
digital structures were brought about, the grub-hunting Lemur subsisted on the 
necessary proportion of fruits and other food more readily obtainable under the 
* Owen, ‘On the Nature of Limbs,’ 8vo, 1849, p. 86. 
t+ De Maillet, ‘Telliamed, ou Entretiens dun Philosophe Indien avec un Missionnaire 
Frangois,’ 8vo, 1755. Buffon, Histoire Naturelle, 4to, tom. xiv., “ Dégénération des Ani- 
maux,” p. 311, 1785. Lamarck, Philosophie Zoologique, 8yo, 1809. Vestiges of Crea- 
tion, Svo, 1846. Wallace, “On the Tendency of Varieties to depart indefinitely from the 
pagel Type,” Proc. Linn. Soc. 1858. Darwin, ‘On the Origin of Species,’ &c. 8yo, 
1859. 
{ Lamarck, op. cit. tom. i, chap. iii, vi. vii. 
8* 
