BIOLOGY OF PHYSA 81 



experiment was also tried upon mosquito larvae {Culex and 

 Anophles) with the result that they would fill themselves with 

 powdered carmine or ground red pepper. 



(3) If the jaws were not in motion when the animal was 

 brought upon the film, a grain of sugar laid upon the mouth 

 would cause an almost instantaneous response, the jaws begin- 

 ning to move. This action was not necessarily long continued 

 unless more sugar was applied. 



(4) If the action of the jaws was started before the experiment 

 began, one or two touches on the mouth with the acid would 

 serve to cause the mouth to close. In the above experiments 

 a fresh snail kept under the same conditions was used each time. 



(5) If acid was applied to the mouth of a fresh snail, the mouth 

 closed or remained so, regardless of whether or not the reflex 

 action of its mouth had been previously started. It then 

 required a steady application of sugar for some time to cause 

 the snail to give a positive response. In one case a snail was 

 lightly touched with the acid on the mouth three times in two 

 minutes, and it took twenty-seven minutes of steady application of 

 sugar to get a brief response of the jaws. After this the periods 

 of response grew gradually more and more frequent. A fresh 

 snail responds to an application of sugar almost instantaneously, 



(6) If a fresh snail was given the sugar first and then followed 

 by acid, the animal would respond for some minutes to the acid 

 as if it were sugar; then with the repeated application of acid, 

 the periods of reflex activity of the mouth caused by it grew 

 less and less. 



b. Experiments on the food reactions of fasting snails. 



The following experiment was tried to see whether reflex 

 action of the mouth could be started by mechanical stimuli 

 alone. vSnails fresh from the field were washed thoroughly, 

 their shells being cleaned with absorbent cotton in filtered 

 water. After they had been rinsed thoroughly, they were 

 severally placed in bacteria dishes which had been thor- 

 oughly cleaned and filled with distilled water. This precaution 

 was taken so that they could not eat from their own and other's 

 shells, and thus start the reflex by chemical stimulus or odor. 

 At first the snails went about giving the reflex action of the 

 jaws, but as time went on, they became more quiet and few 



