164 



PHYSIOLOGY 



CHAP. 



small process, surmounted, according to von Brunn, by a bunch of 

 short, fine hairs (Fig. 66). With Golgi's method it is possible to 

 follow the varicose fibres of the olfactory cells to their dendritic 

 ramifications in the so-called glomeruli of the olfactory bulb, and 

 to determine their relations with the fibres of the olfactory tract 

 (Fig- 67). 



That the olfactory nerve is exclusively the nerve of smell is a 

 physiological theory that has only slowly gained ground, and even 

 to-day there are many who hold no decisive opinion. Galen's 



1 



l\ 







FIG. 6:>. (Left.) Oils ..I tin- i.lt'artmy u-^ion. Highly magnified. (M. Sehultze.) 1, from the 

 frog; 2, from man: n. epithelial cell, extending into a long ramified process; b, olfactory 

 cells; c, their peripheral processns ; r. their extremities, seen in 1 to be prolonged into fine 

 hairs ; d, their central filaments. 



FIG. 66. (Right.) An olfactory cell, human, (v. Brunn.) n, central process prolonged as an 

 olfactory nerve-fibril ; b, body of cell with nucleus ; p, peripheral process passing towards the 

 surface ; c, knob-like termination of peripheral process ; 7i, bunch of olfactory hairs. 



view that the olfactory sense has its seat in the cerebral ven- 

 tricles, and that odorous particles reach it through the foramina 

 of the cribriform plate, was first questioned at the end of the 

 eighth century, when the Greek monk Theophilus Protospa- 

 tarius recognised the olfactory nerve as the organ of smell, by 

 means of which the odorous vapours are carried to the brain 

 during inspiration, and the superfluous moisture is given off in 

 expiration. 



As evidence that the olfactory nerves are the specific nerves of 

 smell Schneider adduced an observation by the Bolognese anatomist, 

 Eustachio Budio, who in 1600 claimed to have known a youth 



