172 PHYSIOLOGY CHAP. 



which is eliminated by his method. The substances examined 

 were : eau de cologne, ylang-ylang, essbouquet, oil of cloves, oil of 

 origanum, oil of peppermint, camphor-water, caproic acid, and 

 caproic acid with addition of piperidine. 



Veress found that even when pain was avoided by careful 

 filling of the nasal cavity, sodium chloride specifically excited both 

 the olfactory end-organs and the endings of the trigeminal nerve, 

 and further pointed out that the sensibility of the olfactory area 

 to this fluid is altered after a strong bath. Veress speaks of 

 symptoms similar to those that occur in coryza, which in his 

 opinion come under the category of olfactory and gustatory 

 sensations. 



As to the effect of the odoriferous substance contained in the 

 saline, Veress says that when the two fluids are completely mixed 

 there is a compound sensation which cannot be accurately defined, 

 in the production of which both the respiratory and the olfactory 

 areas participate. In this compound sensation, according to 

 Veress, the tactile sensations predominate, and the gustatory 

 sensation is weak. That the olfactory area proper is really 

 concerned in it can be controlled by the fact that its sensibility is 

 diminished after a bath. If, for instance, when all the fluid had 

 been removed from the nasal cavity the subject was still able to 

 perceive the odour, Veress considered the experiment a failure, 

 since it was doubtful whether the olfactory groove had been 

 entirely filled. For this reason he questions Vaschide's results, 

 because no appreciable diminution of olfactory sensibility appeared 

 in his experiments. 



After much practice Veress succeeded in distinguishing some 

 odorous substances from others, and divided them into different 

 groups. Thus, for instance, it was difficult to distinguish eau de 

 cologne from ylang-ylang, camphor from oil of peppermint, oil of 

 cloves from oil of origanum, while it was easy to say if the exciting 

 substance were oil of cloves or ylang-ylang, camphor or oil of 

 origanum, oil of peppermint or caproic acid. But he pointed 

 out that it was to some degree possible to identify the group to 

 which any substance belonged, by means of its action on the 

 mucous membrane. He compared this ability to recognise the 

 odorous substances with that by which a man born blind recognises 

 through his tactile sensations certain qualities of external sensa- 

 tions which a normal individual is incapable of knowing by touch, 

 and further claims that associative processes may take part in 

 this act of recognition. Veress came to the general conclusion 

 that an odoriferous substance brought into contact with the 

 olfactory organ in the form of fluid may be regarded merely as a 

 heterologous stimulus for that organ. 



Veress observes that we cannot speak of an olfactory sensation 

 in aquatic animals in the sense in which we use it of mammals : 



