466 journal of Comparative Neurology and Psychology. 



analogy further and to say that as in the cornea pain and not 

 touch appears to be the sensation evoked,^ so also in the membrana 

 tympani one might expect that the slightest pressure would evoke 

 unpleasant sensations — passing into pain — a fact well borne out 

 by clinical observations. 



The anatomical study of the endings in the fibrous tissue inclines 

 one to support the opinion of Deinike that their probable func- 

 tion is to estimate variations in tension which the membrane under- 

 goes. Their position and character seem well adapted to that end. 

 The significance of these being determined, the function of the 

 third variety of ending — the tree arborizations — would appear to 

 offer here a suitable field for psychological investigation. 



The nerve supply in the membrana tympani is usually given as 

 coming from the n. auriculo-temporalis and the n. vagus. It was 

 determined to ascertain the relative amount of distribution of 

 each. The n. auriculo-temporalis in two dogs and two monkeys 

 was sectioned. In one dog the nerve was cut as it emerges from 

 under the mandible; in the other dog and in both monkeys the 

 nerve was cut and removed along with a part of the n. mandibu- 

 laris and the ganglion oticum at the base of the skull. After the 

 operation each animal was kept alive for eight or ten days and 

 then killed. 



As the results from staining the membrana tympani with osmic 

 acid and with Muller's fluid and osmic acid had been unsatis- 

 factory, it was determined to stain by the intravitam methylene 

 blue method and then compare the results over a series of cases. 

 As is well known, the ability of the nerve to react to this method 

 disappears soon after section. As a preliminary it was ascer- 

 tained that 48 hours after section in the dog, cat and rabbit definite 

 changes were so apparent in the degenerated nerve when compared 

 with the corresponding normal nerve as to leave no doubt that 

 these were changes primarily in the nerve. 



In every case both membranes were stained with methylene 

 blue injected simultaneously into both carotids under the same 

 pressure; then the tissue was fixed in molybdate in the usual way. 

 At the same time the external cuticular layer and periosteum over 

 the osseous part of the external auditory meatus of both ears was 



^ Sherrington in Schafer's Physiology, vol. 2, p. 987. 



