652 



BIOLOGICAL EFFECTS OF RADIATION 



he also observed a diminution of granular size and to this, rather than to 

 lowered viscosity, he attributes the change in Brownian movement. 

 With Amoeba rostock, he likewise found increased Brownian movement. 

 Forbes and Thacher (102) treated the eggs of an annelid, Nereis, 

 with beta rays of radium. They then fertilized the eggs and centrifuged 

 them. Irradiated eggs showed somewhat less viscosity than controls. 

 It may be noted that the centrifuge method is an excellent check on the 

 Brownian movement method of determining viscosity, and vice versa, 

 for if protoplasmic granules decrease in diameter, their Brownian move- 

 ment would be accelerated, whereas their movement under the influence 

 of centrifugal force would be greatly retarded. 



■■Aa. fc ii 





jLi^iMi 



a 



Fig. 3. — The effect of mild radium treatment on the viscosity of cells of Spirogyra 

 varians. {After Feichtinger, 197.) (a) Control cells. No displacement of chromato- 

 phores by centrifuging. (6) Cells exposed to beta and gamma rays from RaBr2 prepara- 

 tion of 4 mg. radium equivalents. Chromatophores almost completely displaced by same 

 centrifuge treatment as used on control (3a). (c) Cells treated with alpha rays from 

 polonium preparation of 0.33 mg. radium equivalents. Same time of centrifuging as 

 in 3 a, h. 



Rochlin-Gleichgewicht (317) exposed cells of Elodea and Ptery- 

 gophyllum to radium emanation and found first an increase in rate of 

 streaming and then a decrease. The results were interpreted as indicat- 

 ing first a decrease of protoplasmic viscosity, and then after longer or 

 stronger dosage, an increase. The work of Rochlin-Gleichgewicht is 

 of considerable interest and will be discussed further below. 



Feichtinger (97) centrifuged Spirogyra cells following exposure to 

 alpha, beta, and gamma rays. A number of polonium preparations 

 were used as a source of alpha rays; an amount of RaBr2 considered 

 equivalent in activity to 4 mg. of element was used in experiments with 

 beta and gamma rays. Weak radiation caused a liquefaction of proto- 

 plasm, further exposure an increase in viscosity, and finally a coagulation 

 (compare Figs. 3 and 4) ; Feichtinger used two species of Spirogyra. 

 In the smaller, the alpha particles penetrated the whole cell, whereas in 

 the larger species they penetrated only one-fifth of the diameter. In 

 these larger cells, the effect seems to be propagated, for the result is 



