INNERVATION OF INTEGUMENT OF CHIROPTERA 331 



End-bulbs and terminal corpuscles no doubt are tactile in 

 function, but their depth below the surface of the epidermis pre- 

 cludes any probability that they aid in the perception of con- 

 densation pressures of the air. 



In connection with the question as to which of the two sensory 

 endings mentioned above functions to the greater extent in the 

 perception of atmospheric pressures, it should be pointed out that 

 the area of the integument supplied by superficial nerve rings is 

 insignificant in comparison with the area supplied with nerve 

 end-knobs. Likewise, the number of terminal fibers of the rings 

 is not to be compared with the enormous number of end-knobs in 

 the epidermis. 



As is well known, the human cornea is very sensitive to delicate 

 tactile stimuli. Cohnheim ( '67) has shown that the only type of 

 perceptor to be found in the cornea is that of free nerve termi- 

 nations. 



Goldscheider, in 1886, determined by experimentation the lo- 

 cation of tactile spots on his arm, and then removed for study 

 pieces of skin containing them. Here, also, the only sensory 

 structures revealed by a histological examination were free nerve 

 terminations. 



The evidence thus leads to the conclusion that free nerve termi- 

 nations are more important in the tactile reaction than are the 

 superficial nerve rings of hairs. 



It is not, of course, to be inferred that all the free end-knobs 

 function alone as pressure perceptors, for, as is well known, the 

 sensory nerves of the human skin mediate at least four different 

 qualities of sensations, namely, pressure, warmth, cold and pain. 

 But the number of nerve end-knobs in the skin is so great, and the 

 latter in the bat is so sensitive to delicate tactile stimuli, that the 

 number of free nerve terminations in the epidermis functioning 

 as pressure perceptors must necessarily be very large. 



To sum up, then : The writer is i'nclined to think that the most 

 reasonable explanation of the avoidance of obstacles by blinded 

 bats involves the assumption that condensations of the atmos- 

 phere are set up between the object and the approaching bat, and 



