254 CHARLES E. BILLS. 



aqitatilis group gained a long-enduring ascendency over all other 

 bacterial forms. 2 As this culture supported the finest growth of 

 paramecia that I have ever seen, it is interesting to note that 

 Hargitt and Fray (1917) and Phillips (1922) maintain that 

 simple bacterial mixtures do not provide as good a food for 

 Paramecium as the usual complex natural mixtures. 



Alcohols The six simplest monatomic alcohols were em- 

 ployed : Methyl, ethyl, n-propyl, z-propyl, u-butyl, and f-butyl. 

 All were of good purity. Dilutions in spring water were pre- 

 pared volumetrically, with a micro-burette, a fresh solution being 

 employed for each observation. 



The Effect of Lethal Concentrations of the Alcohols One 

 clone of P. aurelia and two of P. caudatuni were treated with 

 such strengths of the four normal alcohols as sufficed to kill them 

 in from 30 seconds to 30 minutes. The strongest concentration 

 used was 1 5 per cent methyl alcohol ; the weakest was 0.8 per 

 cent butyl. All other strengths were intermediate. In about 

 300 individuals the process of dying was observed under a mag- 

 nification of 700 diameters. 



Wide variations disregarded, the phenomena usually observed 

 follow in order : Incoordination and inactivation of body cilia ; 

 discharge of trichocysts ; arrest of contractile vacuoles ; modifi- 

 cation of cyclosis in course and diminution in rate; bending of 

 body to a crescent ; convulsive rearrangement in posterior part, 

 producing " Indian club " shape ; arrest of undulating membrane 

 in gullet ; and at death, change in appearance of protoplasm 

 to opaque and yellowish, cessation of Brownian movement, oc- 

 casional formation of blisters by elevation of cuticle, and some- 

 times rupture of ectoplasm with discharge of endoplasm into 

 the blisters. 



Three points in blister formation warrant further mention: 

 (i) The lower alcohols give rise to a feiv blisters which grow 

 rapidly, whereas the higher ones result in many blisters which 

 grow slowly. 



(2) The existence of " susceptibility gradients " in Para- 

 mecium is nicely demonstrated in blister formation. Blisters 



I am much indebted to Dr. Percy D. Meader, of the School of Hygiene and 

 Public Health, for the bacteriological examination of this unusual culture. 



