528 A.H. Estahrook 



at 24 hours they measured 160.6 X 51.7 microns. They were at 

 that time shorter than the controls, which had not been treated 

 at the beginning with the alcohol. At the age of 48 hours, the 

 control had increased from 6 to 9 specimens and measured 187.3 

 X 53.7 microns, while those that had been treated with the alco- 

 hol for 30 minutes after fission, and then placed in hay infusion, 

 had increased from 6 to 1 1 specimens, and measured 184.9 ^ 59-4- 

 At 48 hours the Paramecia had entirely recovered from the effects of 

 the initial treatmentwith alcohol and had regained their normal size. 

 Thus we find that ']\ per cent alcohol inhibits growth completely, 

 and that the inhibitory effect lasts for some hours after the ani- 

 mals have been removed from it. But finally the inherent tend- 

 ency to grow overcomes the effects of the alcohol, and the speci- 

 mens regain their normal size and rate of growth. 



Resistance of Adult and Tonng to Alcohol 

 There is no such marked difference in the resistance of a young 

 and adult Paramecia to strong solutions of alcohol as we find with 

 the other chemicals. In a 5 per cent solution young and adults 

 die in about the same time (2 to 3 hours). In a 3 per cent solution 

 the adults are slightly more resistant than the young, living in the 

 solution about 12 hours, while the young die in about 5 hours. 



The relation of alcohol to growth casts some light in the role 

 of osmotic pressure in producing the effects of chemicals on growth. 

 We find that nearly normal growth takes place in 2 per cent 

 solution of alcohol; this has an osmotic pressure of 8.24 atmos- 

 pheres, while Paramecia die quickly in a -^-^- solution of NaCl, with 

 an osmotic pressure of but 4.55 atmospheres. This indicates 

 that changes in osmotic pressure have only a small part in the 

 effects of these chemicals upon growth. 



Thus the effects of alcohol on growth in Paramecium are in a 

 general way similar to the effects of the other chemicals studied. 

 The stronger solutions, 5 per cent and 3 per cent, inhibit growth 

 somewhat, and the animals finally die. Normal growth takes 

 place in I per cent alcohol. No evidence was found that minute 

 quantities of alcohol increase growth. The adult Paramecia are 

 slightly more resistant to alcohol than the young. 



