OLFACTORY NEKVES. 31 



is usually very acute in these animals. Upon dividing or ex- 

 tirpating the olfactory bulbs, "after the animal had com- 

 pletely recovered, it was deprived of food for thirty-six or 

 forty-eight hours ; then, in its absence, a piece of cooked 

 meat was concealed in a corner of the laboratory. Animals, 

 successfully operated upon, then taken into the laboratory, 

 never found the bait ; and nevertheless, care had been taken 

 to select hunting-dogs." ' This experiment is absolutely con- 

 clusive ; more so than those in which animals deprived of the 

 olfactory bulbs were shown to eat faeces without disgust, 2 for 

 this sometimes occurs in dogs that have not been mutilated. 



Comparative anatomy shows that the olfactory bulbs are 

 generally developed in proportion to the acuteness of the sense 

 of smell. Pathological facts also show, in the human subject, 

 that impairment or loss of the olfactory sense is coinci- 

 dent with injury or destruction of these ganglia. A large 

 number of cases observed by Schneider, Rolfinck, Eschricht, 

 Fahner, Valentin, Rosenmiiller, Cerutti, and Pressat, be- 

 tween the years 1600 and 1837, are cited by Longet, in his 

 elaborate treatise on the nervous system, in which the sense 

 of smell was lost or impaired from injury to the olfactory 

 nerves. 3 A case, reported by Hare, in 1821, showed total 

 loss of smell from a disorder of the bones of the head. In 

 this case, an examination was made after death and " the eth- 

 moid (sieve-like) bone, which is naturally furnished with nu- 

 merous minute openings for the transmission of branches of 



1 VULPIAN, Lemons sur la physiologic generate et comparee du systeme nerveux, 

 Paris, 1866, p. 882, note. 



2 Schiff, in a very interesting series of observations on dogs, noted that 

 these animals, deprived of the olfactory nerves, would drink their urine and eat 

 food mixed with their faeces, while this was not observed in other animals, of the 

 same litter, that had not been operated upon. The experiments were made with 

 great care and upon young animals ; and they show conclusively that the olfac- 

 tory nerves preside over the sense of smell. (SCHIFF, Der erste Hirnnerv ist der 

 Geruchsnerv. Untersuchungen zur Naturlehre, etc., Giessen, 1860, Bd. vi., S. 

 254, et seq.) 



3 LONGET, Anatomic et physiologic du systeme nerveux, Paris, 1842, tome ii., 

 p. 38. 



133 



