278 ■ J. S. NICHOLAS 



The experiments in the partitioned aquarium (summarized 

 in tables 2 and 3) show that animals possessing sight respond 

 to stimuli, which because of their non-diffusibility have no 

 effect upon the olfactory organ. The animals which have been 

 deprived of sight can respond only to diffusing substances. In 

 every case, the animals which could use neither sight nor smell 

 are negative to all forms of olfactory stimulus. 

 • Parker, in his work on fishes, found that the organs of the lateral 

 line and the general chemical sense which are present in the skin 

 had to be occluded in his analysis of results. This was accom- 

 plished by painting the animals with magnesium sulphate. 

 This method was tried upon the Amblystoma adult to see if a 

 definite factor of skin sensitivity might be present, but with no 

 result. The use of alkalis or acids such as were employed by 

 Parker and Sheldon ('12) or those used by Crozier ('16) might 

 show the nature of this sense in the larvae of Amblystoma, but 

 in relation to the stimuli employed, the skin sense was not shown 

 to be in any sense discriminatory. 



Parker and Sheldon ('12) point out that much of the work 

 done by Aronsohn ('86) in which he uses oil of cloves in order to 

 test the sense of smell in the goldfish, is inconclusive because of 

 the use of an irritating substance. In their own experiments, 

 they used normal substances for testing the olfactory sense. 



The results obtained by Risser ('14) with the odor-stream 

 apparatus are inconclusive. He states in his summary: "Odor 

 streams specific in character, made to flow over and into the 

 nasal openings stimulate the olfactory sense organ; such stimu- 

 lation causing definite motor activities to follow," and further, 

 "appropriate operation are confirmatory that stimulation by 

 such odor streams is olfactory. Section of the olfactory tract 

 inhibits the reactions. Olfactory stimulation and reaction are 

 not affected by section of the ophthalmic branch of the trigeminal 

 nerve." 



The materials which Risser used and which, therefore, are 

 to be assumed as odor streams 'specific' in character, are a large 

 number of essential oils together with some food substances. 

 A glance at his data shows that positive reactions were obtained 



