632 JONATHAN RISSER 



being bent down between the forelegs, the body raised from the 

 ground and best described as humpbacked. Et^er or alcohol 

 did not produce reactions so decidedly vigorous, though the 

 toads retreated quickly from the tube. 



The respiratory movement was retarded by all the substances • 

 that stimulated the olfactory end-organ. Tests made with the 

 odor stream when the act of inspiration was suppressed were 

 devoid of any resultant motor activity. 



After the earlier tests with ammonia, ether, etc., the essen- 

 tial oils were used and some were found to be more effective in 

 calling forth characteristic reactions than others. Some were 

 entirely negative in effect, as, for instance, castor oil, cod liver 

 oil, and olive oil. 



"V\Tiat reactions could be considered as directly called out by 

 the stimulation of the olfactory organ? 



WTien the odor stream from oil of cloves or pennyroyal was 

 allowed to spread over the anterior region of the head and pre- 

 sumably enter into the nasal cavity with the inspired air, the 

 first motor act consisted of a slight bending down of the head, 

 away from the nozzle of the tube, and a cessation of the respira- 

 tory movements. If the tube were removed quickly, the toads 

 soon resumed the normal position and the respiration move- 

 ments went on again with little interruption. If the odor 

 stream was allowed to flow continuously upon the nostrils, 

 respiration was entirely suppressed for some time. Often the 

 toad made motions with the forelegs resembling wiping. When 

 very much stimulated by the stream the animals moved away 

 from the tube. The bending of the head was most noticeable 

 when the toads were partly hidden in the sand. At such times 

 respiration ceased, the head was bent more anteriorly and the 

 animals endeavored to burrow down into the soil. The act of 

 burrowing could be hastened by directing the tube repeatedly 

 at the nostrils during such a test. This position of. being partly 

 buried in the soil was most favorable for observation. When 

 thus buried the animals did not move about and the stream 

 could be directed more accurately against the nostrils than at other 

 times when the animals were free to move about. 



