PROBLEM OF CAVE BLINDNESS 249 
the rudimentariness may be in some cases imposed 
on each individual generation, and the result of 
peculiarities of nurture rather than of hereditary 
nature. 
This is, of course, a matter for experiment, and 
some data are already available. Thus, Ogneff 
kept goldfishes for three years in absolute darkness, 
taking care to give them plenty of room and plenty 
of food. The result was total blindness; even the 
rods and cones of the retina disappeared. We may 
suppose, then, that if some goldfishes were washed 
into a cave, they might become blind. It is likely 
enough too (it ought to be tried) that their offspring 
would show even greater degeneration of the eye, 
being exposed to darkness from birth. If the 
degeneration of the eye continued to increase after 
the second generation (and this also should be 
tested), a case would be forthcoming in support of 
the theory that individually acquired modifications 
may become in some measure part of the inherit- 
ance. But the evidence of this is not as yet 
forthcoming, and Ogneff’s experiment should be 
repeated by other experimenters and on other 
fishes. 
It is a very instructive fact that the wan Proteus 
from the caves, which shows no pigment in its skin, 
becomes rapidly spotty and then dark-colored when 
brought into the light. It responds like a photo- 
graphic plate, and the eggs produced in the light 
develop into dark-colored offspring. How slow 
one should be to infer the absence of a potentiality 
