Effect of Chemicals on Grozuih 



521 



Growth in i-200,000 and I- 2^0,000 strychnine. It was noted 

 above that certain investigators had found that minute quantities 

 of strychnine mcreased the division rate in Paramecium; in 

 order to determine whether increased size accompanied this 

 increased rate of division, more dilute strengths were used. In 

 both 1-200,000 and 1-250,000, growth was exactly the same as 

 in the controls (see tables XXX and XXXI). There was no 

 evidence at any time of either increased size or increased rate of 

 division. 



Comparative Resistance of Adult and Touug Paramecta to 



Strychnine. 



Twenty adult Paramecia and 20 young Paramecia from 

 the same stock culture were put into 1-25,000 strychnine solution. 



RESULT 



The same experiment was again tried using 1-50,000 strych- 

 nine in place of the 1-25,000. The results follow. 



It is evident from these experiments that adult Paramecia have 

 a much greater resistance than young specimens to the stronger 

 solutions of strychnine. *\!||l 



Summarizing the effects of strychnine, we find that when speci- 

 mens just after fission are introduced into hay infusion contain- 

 ing strychnine at concentrations of from 1-12,500 to 1-75,000 a 



