436 



ROBERT W. HEGNER 



because of lack of time to keep them going. Sufficient data 

 were obtained, however, to prove that these organisms are able 

 to live and reproduce in a medium containing from 0.25 to 1 per 

 cent of alcohol. Three offspring were obtained from one of the 



Arcella dentata. Family 14. Camera-lucida sketches (X 207) 



Fig. 

 showing: 



A = the original progenitor; with sixteen spines and diameter of 34 units. 



B = the first offspring after A was placed in a solution of one drop of sodium 

 silicate to 50 cc. of normal medium. 



C = the third offspring of A, produced while A was in a solution of one drop 

 of sodium silicate to 100 cc. of normal medium. 



D = fourth offspring of A, produced immediately after A was transferred 

 from the sodium silicate solution back to normal medium. 



E = seventh offspring of A, produced immediately after A was transferred 

 from normal medium to sodium silicate solution. 



F = a specimen of the seventh generation after continuous subjection to 

 sodium silicate. 



specimens that was kept in a 0.50 per cent solution of alcohol; 

 two of these and the parent were still alive thirty-five days after 

 the experiment was begun. The rate of fission was very slow, 

 probably because of the effects of the alcohol upon the food. 



