CHANGES FOR ADAPTATION IN THE MOLE 345 
To gain some idea of how these organs were utilized, a mole 
was placed in an aquarium with a hard dry bottom. It soon be- 
came very restless, continually moving about and probing with 
its nose for a means of escape. The tactile hairs on its snout 
and the specialized papillae are apparently the chief sources of 
information which guide it in locomotion. 
Eimer (’71) gives a good description of the touch organs in 
the snout of the mole. He says the whole surface is arranged 
in papillae, each of which is supplied with a nerve bundle whose 
axis cylinders have a definite arrangement. There are from 
one to three in the center and these are surrounded by a ring of 
from fifteen to twenty other axis cylinders. 
Bielschowsky (07) has reviewed Eimer’s work and made 
further observations. He also mentions the very rich nerve 
supply to Eimer’s organs, as he calls them, but claims that he 
finds as many as thirty endings to each organ. He estimates 
that the total number of these organs is about 150,000. The 
snout is thus so richly supplied with end-organs that it is a 
very sensitive tactile organ. The extreme tip of the snout is 
especially well supplied with these nerves. 
Besides this specialized tactile region, the mole has also special 
tactile hairs on the manus. These were discovered by Merkel 
in 1880. More recently Kazzander (’09) has studied the tactile 
hairs and describes their arrangement. They form a half-circle 
on the palmar margin. Some of these he considers tactile in 
function while others are not. He found a similar arrangement 
of these hairs in both sexes. He thinks their function is to assist 
the animal in digging and in securing its food. In a later paper 
(10) he describes similar hairs extending to the toes on the hind 
feet of both sexes. Though these hairs on the hind feet look 
very much like the tactile hairs on the manus, a microscopical 
study shows the absence of special nerves to them. He does 
not, therefore, consider them tactile in function. These results 
have been verified by Henneberg (’15). 
Beddard (’16) finds that nearly all mammals possess a tuft of 
from one to twenty strong vibrissae, located upon the wrist, 
which is innervated by a branch of the radial nerve. He has 
