INNER^ ATION OF INTEGUMENT OF CHIROPTERA 329 



ter is transferred to the nerve ring in such a way that objects are 

 perceived and avoided. 



In 1873, Redtel liberated a blinded bat in a room in which had 

 been placed numerous threads. The animal avoided the threads 

 successfully. From the abundance of nerves found by Schobl in 

 the flying membrane, and from his own experiments, Redtel in- 

 ferred that it was possible for bats to perceive the slightest change 

 of air pressure upon the wings. 



Sabussow ('10), like Jobert, was of the opinion that air currents 

 were set up between the object and the approaching blinded 

 animal, and that by means of these currents the nerves of the 

 hairs were affected. 



A few investigators have held that the organs for the perception 

 of the delicate stimuli, which bring about these avoiding reactions, 

 are located in the internal ear. ♦ 



Jurin ('98), experimenting upon living bats, observed that when 

 their organs of hearing were destroyed, they were unable to avoid 

 obstacles placed in their way. A mutilation so severe as this, 

 however, would certainly produce shock effects which might 

 affect very considerably the results of the experiments. 



Hahn ( '08) caused a large number of mutilated bats (blinded, 

 ears cropped, etc.) to make a given number of flights in an en- 

 closure through which numerous wires had been stretched. He 

 agreed with Jurin that objects are perceived by the flying animals 

 chiefly through sense organs located in the internal ear. The evi- 

 dence for this was obtained by closing the external auditory 

 meatus with plaster of Paris, whereupon he found that the per- 

 centage of 'hits' (collisions with wires) was much higher for this 

 experiment than for that of any of the others. The fact should 

 not be overlooked that the placing of a hard substance like the 

 one used in the meatus, and possibly against the sensitive tym- 

 panic membrane, is likely to interfere seriously with the normal 

 functioning of the nervous system. 



It is thus seen that the weight of evidence favors the view that 

 condensations (pressures) of the atmosphere set up between the 

 obstacle and the blinded bat stimulate sensory structures in the 

 integument. 



