754 
DR. CARPENTER ON THE MUTUAL RELATIONS OF 
minute Entomostracous Crustacea is well known. Their development is greatly re- 
tarded by the want of it ; and the exuviation of their shells, which normally takes 
place at short intervals when they have attained their complete form and size (ap- 
parently for the purpose of freeing them from the minute plants with which their sur- 
face becomes clothed), is much less frequently performed*. With these facts before 
us, we can scarcely refrain from suspecting that the deprivation of light may be the 
cause of the atrophy of the visual organs in certain animals which pass their whole 
lives in complete seclusion from its influence. This condition, which has been long 
known to exist in the common Mole, and also in the Proteus anguineus, and which 
has also been discovered in the Amblyopsis spelceus, a fish inhabiting the waters of 
the Great Cave of Kentucky, has recently been detected in a considerable number of 
species of Insects discovered in the very caverns of the Tyrol whose waters afford a 
habitat to the Proteus'f . It may be supposed that the non-development of eyes in all 
these animals is a part of their original constitution, and is to be looked upon as an 
example of the adaptation of their organisms to the peculiar conditions of their exist- 
ence ; and such a view cannot at present be positively disproved. But the actual de- 
pendence of the nutrition of the visual organs, or (at least) of the nervous apparatus 
which forms the essential part of them, upon the continued agency of light, appears 
from the well-known fact, that if, by the complete opacity of the cornea, light is 
entii’ely prevented from entering the eye, the retina and the optic nerve become 
atrophied, and in time altogether lose their characteristic structure; thus clearly in- 
dicating the direct influence of light in keeping up those nutritive actions, by which 
the integrity of that structure is normally maintained. 
That Electricity, also, has an important influence on the operations concerned in 
the development and maintenance of organized structures, can scarcely be doubted by 
any one who duly considers the proofs of the disturbance of the electric equilibrium 
in those parts of vegetable as well as animal bodies which are in a state of greatest 
functional activity, afforded by the observations and experiments of Prof. Matteucci 
and others. At present, however, it would be premature to make any positive state- 
ment as to its modus operandi ; although it would certainly appear most probable 
that it is more directly related to the chernico-vital changes of composition which 
take place in the living body, than to the operations of cell-growth, multiplication, 
and development, properly so called. 
If the views advocated in this communication be correct, it follows that not merely 
are the materials, withdrawn from the inorganic world by vital agencies, given back 
to it again by the disintegration of the living structures of which they have formed 
* See Dr. Baird’s “ Natural History of the Entomostracous Crustacea” (published by the Ray Society), p. 
192 . 
t Specimen Faunce Subterranea , Bidrag til den underjordiske Fauna, ved J. C. Schiodte : Kjobenhavn, 
1849 . 
