634 JONATHAN RISSER 



Bergamot and cedar oil resulted in fewer reactions than oil of 

 clove and oil of pennyroyal, showing them to be less stimulating 

 than the other oils. 



As already indicated, the stimulus was efl'ective onlj^ while 

 inspiration was in progress, for pressure of the stream was so 

 slight that it could not force the odorous particles into the nos- 

 trils. The reactions were not characteristic of the different odors. 

 It might be said that the reactions differed in degree, only, since 

 there were only differences of vigor with which the reactions were 

 executed. Even individuals differed in this respect at different 

 times during the trial periods. Other factors such as tempera- 

 ture or tendency to hibernate may have had some influence in this 

 aspect of the reactions. Absolute parity of the tests could of 

 course not be obtained. 



The relative effectiveness of the odors in stimulating the 

 receptors was as follows : Most effective and approximately equal 

 were oil of cloves, and oil of pennyroyal; less effective were oil 

 of rose geranium and cedar oil; and least effective, with reactions 

 infrequent, were bergamot oil and carbolic acid. 



Odors from castor oil, olive oil, cod liver oil, living meal- 

 worms, earthworms, dungworms, cockroaches, decaying meat 

 and decaying leaves in soil were without effect. 



6. Controls and operations 



The controls used in the tests seemed to be confirmatory 

 of the presence of the olfactory function; yet a possibility existed 

 that other receptors had been stimulated at the same time. 

 The ophthalmic branch of the trigeminal neijve supplies the region 

 of the head anterior of the nostrils, with some fibers possibly 

 present within the nasal capsule. This being so, stimuli coming 

 to this region of the head could call forth reactions easily through 

 this branch as well as through the olfactory organ. To ascer- 

 tain whether this branch had been stimulated several sets of 

 experiments were tried. 



The nostrils were closed by suturing with silk thread. Closing 

 the nostril in this manner was of more serious consequence to the 



