514 A .H. Estahrook 



At the end of five minutes, though there was some growth, 

 those in the nicotine were not quite so large as the controls. At 

 30 minutes, they were still growing, but continued to be smaller 

 than the controls. At 60 minutes, they began to decrease in 

 size. At the end of 2 hours, of 11 specimens in the nicotine, 4 

 were alive and 7 dead. It is to be noticed that some growth took 

 place in a solution of nicotine which later killed the organism. 



Grozvth in 1-^^,000 nicotine. In one part of nicotine to 5,000 of 

 hay infusion, growth took place in the same general way as in the 

 1-2,5000 solution (see table XX). 



The Paramecia grew in the nicotine, but were not at any time 

 so large as the controls. At the age of 9 hours, those in the nico- 

 tine measured 175.2 X 49-2 microns, while the controls were 197.7 

 X52.5. At the age of 24 hours, those in the nicotine were begin- 

 ning to die, and at 48 hours, all those in the nicotine were dead. 



Growth in 1-10,000 nicotine. In a i-io,ooo solution of nico- 

 tine, the Paramecia grew at about the same rate as those in the 

 1-5,000 (see table XXI), remaining somewhat behind the con- 

 trols. 



The difference is not great, but the results indicate a slight in- 

 hibition of growth caused by this amount of nicotine. All those 

 in the nicotine were dead at 45 hours. 



Growth in 1-20,000 nicotine. The results with 1-20,000 nico- 

 tine were variable (see table XXII). 



Up to 5 hours, the growth was not evidently affected. At later 

 periods the specimens in the nicotine were sometimes smaller, 

 sometimes larger, than the controls. At 24, and 48 hours, they 

 were distinctly smaller. Thus the effect of such a quantity of 

 nicotine shows only after a considerable period. 



Growth in 1-^0,000 nicotine. In 1-30,000 nicotine, growth took 

 place as in the control (see table XXIII). 



At the end of 24 hours, the measurements in the nicotine were 

 193.2 X 63.9 microns, while the controls measured 187.5 X 68.7 

 microns. The difference is without significance; it is partly due 

 to the fact that one of the controls had divided, the two small 

 specimens so produced reducing the average length. 



