CHEMICAL SENSITIVITY OF TAESI OF PYEAMEIS 79 



did the same excepting the last day of the experiment, when its 

 responses suddenly dropped to 0. The total weighted response 

 of all four specimens to the quinine solution was 84.7 per cent, as 

 opposed to 100 per cent for IM saccharose and 51.6 per cent for 

 2M NaCl. The amount of response produced by quinine was, 

 therefore, intermediate between the other two substances. 



A comparison of the curves for the quinine solution with those 

 for sodium chloride (fig. 3) shows in every animal that there was 

 a great diversity in the two responses. At times, the amount of 

 response to each stimulus was the same; at other times, it was 

 totally different. Here again, therefore, we must conclude that 

 the two stimuU were differentiated. 



A comparison of the saccharose and quinine curves yields no 

 such conclusive evidence as the case above. For, while the two 

 curves exhibit a rather wide divergence in animal no. 12, they 

 very closely approximate one another in the other three animals. 

 In this instance, however, there were distinctive differences of 

 another sort. The rapidity with which the proboscis was ex- 

 tended to IM saccharose has already been pointed out. As a 

 comparison of the figures in table 2 will show, the response to 

 quinine was very much slower. Thus, in animal no. 11 the 

 average time required by quinine was seven to eight times that 

 required by saccharose; in no. 12, thirteen to fourteen times; 

 in no. 13, six to seven times, and in no. 22, three to four 

 times. With IM saccharose the extension of the proboscis 

 began very shortly after the application of the stimulus and 

 was rapidly completed. This was not the case with quinine. 

 As a rule, the application of this stimulus was followed by a 

 latent period lasting from a few seconds up to as many as 

 sixty seconds, during which there was no sign of response. Then 

 followed a period of reaction, beginning with slight relaxations 

 of the proboscis which more or less gradually increased until ex- 

 tension was complete. The period of reaction also lasted from 

 a few seconds up to fifteen or twenty seconds or even longer.^ 



^ The long latent period together with the long period of extension necessitated 

 the prolongation of a number of trials with the quinine solution from the usual 

 duration of one minute to two minutes. 



