THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL. 



Vol. XII. MARCH, 1891. No. 3. 



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The Partial Occlusion of the Olfactory Lohe in the Canidas. 



By PIERRE A. FISH, 



ITHACA, N. Y. 



[Read at the Boston Meeting of the American Anatomists, i8go.] 



[With Frontispiece.] 



Broca is, perhaps, the only anatomist who has attempted to describe 

 the structiu'c of the dog's olfactory lobe with reference to the occlusion 

 of its cavity. Meynert in his article on the " Brain of Mammals " gives 

 a figure of a canine hemi-cerebrum containing a rhinoccele (olfactory 

 ventricle). Obersteiner in a more recent work on " Central Nervous 

 Organs " gives a similar diagram Huguenin, Owsiannikow, and others 

 in their study of this region in different mammals, including the dog, 

 have never hinted at anything contrary to its existence. 



Embryology demonstrates that the olfactory lobes in all mammals are 

 hollow at a certain stage of development, and the persistence of this 

 embryonic feature to an adult stage may easily be verified in the ele- 

 phant, horse, cow, sheep, pig, rabbit, cat, and probably the majority 

 of quadrupeds. Dogs are proverbially noted for the acuteness of their 

 sense of smell ; but it is doubtful if it is due to the partial occlusion of 

 this cavity. 



In Broca's classification, those mammals, especially the carnivora, in 

 which smell is highly developed, are osmatic ; those in which it is 

 poorly developed are anosmatic, and are represented by man, monkeys, 

 and cetacea. 



Professor Turner, of Edinburgh, has proposed the more specific terms, 

 macrosmatic for those included in Broca's osmatics, microsmatic repre- 

 sented by man and monkeys, and anosmatic represented by the dolphin, 

 in which the olfactory lobes are said to be absent. 



The dog in this classification seems to hold an anomalous position, 



Copyrightj 1891, by C. W. Smiley. 



