ACTION OF X-RAYS UPON PARAMCECIA. 



61 



Experiment 

 May 31, 1916, A.M. 

 Series No. i, Culture 2 parts 

 (by volume), Stain 8 parts 

 (by volume) 



Series No. 2, Culture 2 parts 

 (by volume) , Stain 7 parts 

 (by volume) 



Series No. 3, Culture 2 parts 

 (by volume), Stain 6 parts 

 (by volume) 



Series No. 4, Culture 2 parts 

 (by volume) , Stain 5 parts 

 (by volume) 



Series No. 5, Culture 2 parts 

 (by volume), Stain 4 parts 

 (by volume) 



Series No. 6, Culture 2 parts 

 (by volume), Stain 2 parts 

 (by volume) 



Series No. 7, Culture 3 parts 



(by volume), Stain 2 parts 



(by volume) 

 Series No. 8, Culture 5 parts 



(by volume), Stain 2 parts 



(by volume) 



Observations of 

 June i, 1916, A.M. 

 Series No. i, paramoecia 



spherical in shape, 



motionless, nucleus 



stained. 

 Series No. i, paramoecia 



spherical in shape, 



motionless, nucleus 



stained. 

 Series No. i, paramoecia 



spherical in shape, 



motionless, nucleus 



stained. 

 Series No. i, paramoecia 



spherical in shape, 



motionless, nucleus 



'stained. 

 Series No. i, paramcecia 



spherical in shape, 



motionless, nucleus 



stained. 

 Series No. 6, paramcecia 



sluggishly active, few 

 motionless with 



stained nuclei. 

 Series No. 7, all active. 



Observations of 

 June 2, 1916, A.M. 



Series No. i, paramcecia 

 spherical in shape, 

 motionless, nucleus 

 stained. 



Series No. i, paramcecia 

 spherical in shape, 

 motionless, nucleus 

 stained. 



Series No. i, paramcecia 

 spherical in shape- 

 motionless, nucleus 

 stained. 



Series No. i, paramcecia 

 spherical in shape, 

 motionless. nucleus 

 stained. 



Series No. i, paramcecia 

 spherical in shape, 

 motionless, nucleus 

 stained. 



Series No. i, paramcecia 

 spherical in shape , 

 motionless, nucleus 

 stained. 



Series No. 7, all active. 



Series No. 7, all active. Series No. 7, all active. 



of the stain did not result apparently in a further absorption. 

 The experiments demonstrated, moreover, that the various stains 

 possessed a differing degree of toxicity for these organisms similar 

 to that which had been noted by Lewis in his study of the action 

 of vital stains on bacteria. 



Practically it was found to be more convenient to stain organ- 

 isms for a period of from one and a half to two hours in a solution 

 of a degree of concentration somewhat greater than that which 

 could be tolerated without injury for a period of twelve hours. 

 At the expiration of this staining period the organisms were 

 transferred to the diluent tap water in the proportion of ten 

 volumes of the water to one volume of the organism and stain 

 and studied during the succeeding days. Through an empirical 

 process of experimentation the approximate degree of concentra- 



