64 W. M. BALDWIN. 



The next and final step in the experiment consisted of a study 

 of the action of the rays upon stained cultures of paramcecia. 

 The staining of the organisms was carried out according to the 

 method which I have detailed above. The energy. utilized was 

 that which has also been given above. A reference to the 

 experiment notes will give an idea of the results obtained. 



On May 10, 1916, series C, consisting of six paramcecium 

 cultures, was rayed beginning at 2:00 P.M., each for a period of 

 12.5 consecutive minutes. These cultures had previously been 

 stained for 105 minutes in a trypanblau solution of the strength 

 o.ooi gm. of the dry stain to 220 c.c. tap water, of which mixture 

 four volumes were added to one volume of the culture. The 

 staining was begun at u 115 A.M., and the raying at 2:00 P.M. 

 At the expiration of the raying period, all of the organisms were 

 very sluggish in action. At the expiration of forty-eight hours 

 all were dead. Controls to these experiments were conducted in 

 which the unstained paramoecia were rayed for an equal time, 

 and paramcecia were stained during an equal time. In both 

 instances the organisms were unaffected. In one series (B) the 

 unstained paramcecia were rayed for a period of 12.5 consecutive 

 minutes and in C during a period of thirty consecutive minutes. 

 Forty-eight hours afterwards the unstained cultures were still 

 alive and vigorous but in series C most of the paramcecia were 

 dead, a few, however, remaining sluggishly active. 



By a continuation of the experiment along this general line, 

 through increasing the concentration of the stam, it was found 

 possible to cause the death of the organisms with an exposure 

 varying from 2.5 to 5 minutes. A reference to the experiment 

 notes of May 18, 1916, verifies this fact. On this day series A, 

 consisting of six cultures of paramoecia, was stained with trypan- 

 blau for two hours (stock solution o.ooi gms. to 200 c.c. tap water, 

 diluted in the proportion of 2 volumes of culture to 8 of stain). 

 These were then rayed for five consecutive minutes, beginning 

 at 10:42 A.M. At 11:00 A.M. a few of the paramoecia were 

 observed to be active though this activity was considerably 

 slowed. The majority, however, were motionless.. Forty-eight 

 hours later a still greater number of paramcecia were dead. The 

 nucleus had assumed a dark bluish color, the cytoplasm had 



