742 The American Naturalist. [September, 
In his discussion on this subject, as well as those of others 
who have adopted his views, Weismann, and his English 
translators, do not always give evidence of having carefully read 
the statements of those who have paid some practical attention 
to cave animals, Weismann only referring to the cases of the 
mole and of the Proteus. For instance, he remarks, “ If disuse 
were able to bring about the complete atrophy of an organ, it 
follows that every trace of it would be effaced (pp. 90 and 292). 
Now in our “Cave Fauna of North America,” published two 
years before the issue of the English translation of Weismann’s 
essays, we have shown from microscopic sections that in the 
different species of blind beetles (Anopthalmus) not only is 
every trace of the optic ganglia and of optic nerves wanting, 
but also every trace of the eyesthemselves. Also in the blind 
myriopods of Mammoth Cave, Scoterpes copei, no traces of the 
optic ganglia, optic nerves, or of any part of the eyes, includ- 
ing the pigment of the retina or the corneal lenses, were to be 
discovered. While in the blind crayfish the degenerate eyes 
are retained, in some individuals of an Asellid (Caecidotaea 
stygia), the eyes may be entirely effaced as well as the optic 
ganglia and optie nerves. On p. 118 of the memoir referred 
to there is a summary view of the effects upon the eyes, optic 
ganglia, and optic nerves, of different Arthropods resulting 
from living in total darkness. 
Again, on p. 87, Weismann makes the following somewhat 
loose statement: “blind animals always possess very strongly 
developed organs of touch, hearing and smell" We have 
laid special emphasis in our essay on compensation by the de- 
velopment of tactile and other organs for the loss of eyesight 
or of eyes in cave animals, and while Weismann's assertion 1s 
true as regards the tactile and olfactory senses, it is curious 
that, from the direct and repeated observations of Dr. Sloan, 
which we quote, the blind fish oceurring in Wyandotte Cave 
is, contrary to Wymar S and to Cope's suppositions, not sensi- 
tive to soun 
'The blind asayah of Mammoth Cave, ånd also the species 
(Orconectes hamulatus) of Nickajack Cave, have, as we have 
ascertained by anatomical investigation, degenerate ears, £O 
