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MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 187 
As regards the origin of the deep-lake fauna of Switzerland, Forel, in his Faune Profonde 
(4 mB ser., 1879, p. 500), concluded as follows: 
1. The lake fauna of our suhalpine regions descended from animals which hare immigrated since the glacial 
epoch. 
2. From the fact that they are immigrants from other regions they hare all had to adapt themselves to the 
special conditions of each lake. 
3. The immigration was made for each of the three faunae in a particular way, viz: 
a. Littoral fauna : by the passive migration of animals already adapted to lake life from other lakes, and by 
the active migration of animals having ascended the rivers and having consequently had to adapt 
. themselves on the spot to a lacustrine life. 
b. Pelagic fauna : by the passive migrations of animals already adapted in other lakes to the lacustrine life. 
c. Deep-lake fauna : by the active or passive migration of animals coming from the littoral or pelagic faun® 
of the same lake and having undergone on the spot an adaptation to the environment. 
Lastly, in his Essai sur la faune profonde des lacs de la Suisse, 1885, Dr. Du Plessis-Gouret 
substantially adopts Forel’s view, which he quotes. He also remarks: 
The animals of the abyssal regions have originated by direct emigration from those which peopled the shores; 
and the former have themselves been brought into the lakes by running water under the form of affluents of all 
kinds, or by the stagnant waters of marshes and ponds communicating with the lakes by means of freshets. Iin 
resume, our littoral lacustrine fauna is only a simple particular case of the fauna of running and stagnant waters of 
the surrounding country, and consequently the deep-lake fauna is but a special offshoot of the littoral fauna, like a 
part of the pelagic fauna, which has in a similar way detached itself from the animal life of the shores. 
It appears, then, to recapitulate, that while the blind fauna of the w r orld is but an almost infini¬ 
tesimal portion of animal life as a whole, it is characteristic of the totally dark abysses of the ocean 
and of lakes as well as of caves. But while the deep-lake fauna and that of caves is generally con¬ 
ceded to be no older than the Quaternary period, that of the ocean abysses is probably much 
older, and directly descended from the Tertiary and even the Cretaceous periods, though it is 
believed with good reason by certain zoologists that all deep-sea life originally emigrated from 
the waters of comparatively shallow depths; namely, within depths less than a thousand fathoms- 
*■* 
THE BEARINGS OF CAVE LIFE ON THE THEORY OF DESCENT. 
So far as we are aware, Lamarck was the first naturalist to refer the atrophy of eyes and loss 
of vision to disuse from a life in darkness, as may be seen by the following extract from the chapter 
in his Philosophie Zoologique entitled “ De l’influence des circonstances sur les actions et les habi¬ 
tudes des animaux, et de celle des actions et des habitudes de ces corps vivans, comme causes qui 
modifient leur organisation et leurs parties.” This work appeared in 1809, many years before the 
discovery of blind animals peculiar to caves. 
Des yeux k la tete sont le propre a’un grand noinbr e d’animaux divers, et font essentiellement partie du plan 
d’organisation des vertdbrds. D6jh n^anmoins la taupe, qui, par ses habitudes, fait trhs-peu d’usage de la vue, n’a 
que des yeux trbs-petits, et k peine apparens, parce qu’elle exerce trbs-peu cet organe. 
L’Aspalax d’Olivier (Voyage en figypte et en Perse, II, pi. 28, fig. 2), qui vit sous terre comme la taupe, et qui 
vraisemblablement s’expose encore moins qu’elle a la lumifere du jour, a totalement perdu l’usage de la vue; aussi 
n’offre-t-il plus que des vestiges de l’organe qui en est le siege; et encore ces vestiges sont tout-h-fait caches sous la 
peau et sous quelques autres parties qui les recouvrent, et ne laissent plus le moindre accfes h la lumifere. 
Le protde, reptile aquatique, voisin des salamandres par ses rapports, et qui habite dans des cavitds profondes et 
obscures qui sont sous les eaux, n’a plus, comme l’Aspalax, que des vestiges de l’organe de la vue; vestiges qui sont 
eouverts et caches de la incnie maniere. 
Voici une consideration decisive, relativement h la question que j’agite actuellement. 
La lumiere ne pdnfetre point partout; consequemment, les animaux qui vivent habituellement dans les lieux oh 
e lle n’arrive pas, manquent d’occasion d’exercer l’organe de la vue, si la nature les en a munis. Or, les animaux qui 
font partie d’un plan d’organisation, dans lequel les yeux entrent nticessairement, en ont dh avoir dans leur origine. 
Cependant puisqu’on en trouve parmi eux qui sont prives de l’usage de cet organe, et qui n’en ont plus que des 
vestiges caches et reconverts, il devient Evident que l’appauvrissement et la disparition mSme de l’organe dont il 
s’agit sont des rdsultats, pour cet organe, d’un ddfaut constant d’exercice (2d edit., i, p. 241). 
In his “Origin of Species” Darwin, after claiming that “natural selection would constantly 
aid the effects of disuse” in the case of moles and the burrowing rodents, then remarks in regard 
