124 Journal of Comparative Neurology 



mental work sometimes by an Olfactometer. For a description 

 of this instrument as well as the process of using it see " Les 

 Odeurs. Demonstrations avec l'olfactometre et le pesevapeur, 

 par M. C. Henry," Paris, 1892. According to the writer of 

 the above, most of the perfumes are of organic origin. There 

 seems to be some relation between the odor and the atomic 

 weight, more or less independent of chemical composition. It 

 is further supposed that perfumes are propagated by the emission 

 of solid, liquid or gaseous particles; hence the laws of diffusion 

 and evaporation may largely control not only the degree of del- 

 icacy of the sense of smell, but perhaps also the apparent mod- 

 alities. At any rate these are fruitful fields of research. 



6. Ziehen says that the number of modalities of smell is 

 very great as compared with the modalities of taste, although 

 there is at present no good classification of the former. The 

 specific names of odors almost always are taken from the odor- 

 ous objects, or borrowed from the nomenclature of some other 

 sense (as violet, rose, sweet, dry, etc. ) With most persons 

 the sensation of smell is exceedingly subjective, and any natural 

 classification is made on this basis. This sense is always very 

 closely associated with the well-being of the individual. The 

 sense of smell is poorly localized in the higher animals, but is 

 very closely associated with the cognitive powers and conse- 

 quently is better localized in some lower animals. Indeed it 

 almost takes the place of a natural language and takes the place 

 of hearing in some cases. The word "taste" is often used 

 when the word "smell" should be employed. We speak of 

 tasting odoriferous substances such as onions, wine, etc., when 

 in reality we only smell them as we hold them in the mouth. 

 This is proved by the fact that the so-called taste of these things 

 is lost when the nose is held or the nasal membrane rendered 

 inert by catarrh. 



7. Central Olfactory Nerve Connections. Methods of extir- 

 pation and subsequent histology have shown that the hippo- 

 campus is the olfactory region or centre in the brain. More- 

 over we find in aquatic animals (fish, dolphin, whale, sharks, 

 rays, etc.) that the entire olfactory lobe is absent, and find in 



