IRRADIATION OF LIVING PROTOPLASM 649 



within the cell, the most characteristic feature of which is the appearance 

 of numerous small vacuoles. 



It is interesting to point out that ultra-violet radiation does cause a 

 vacuolization reaction in diverse types of living systems, and as a matter 

 of fact, vacuolization has constantly been described following all types of 

 radiation. An early observation is that of Ogneff (279). Upon exposing 

 experimental animals to a powerful carbon arc and studying the eyes 

 cytologically, he noticed various necrotic changes in the cells of the 

 corneal epithelium, chief among these being the gradual filling of the cell 

 with small vacuoles ("Kiigelchen") which seemed to appear first near the 

 nucleus. (These effects may, however, have been due to infra-red, 156, 

 377.) Schulze (337) irradiated Rhoeo ( = Tradescantia) hair cells, using 



o 



X2800 A. He describes as the first and most pronounced effect of the 

 radiation the appearance of many small vacuoles in the cytoplasm. 

 As irradiation continued, these increased in size and number. 



Bovie (34, page 14) has described vacuolization in amoeba protoplasm. 

 Thus he says that following treatment of an amoeba with Schumann 

 rays, "Under a high magnification (2200 diameters) the protoplasm was 

 seen to be filled with fine vacuoles which were so numerous that it was 

 converted into a fine froth." 



The protoplasm of sea-urchin eggs is especially interesting because 

 these cells have been used more than any others in physical and colloidal 

 studies of living substance. Upon excessive stimulation, the protoplasm 

 of Arbacia eggs undergoes a violent transformation. Red pigment 

 granules disappear, and numerous vacuoles fill the cell. Typically there 

 is a marked increase in cell volume. The reaction is identical with 

 that which occurs when a cell is violently torn or broken (see above). 

 The vacuolization of sea-urchin eggs was noted by early workers, but 

 its importance was first emphasized by Loeb (241) who referred to it as 

 cytolysis. Ultra-violet rays cause a very complete cytolysis of sea- 

 urchin eggs (133, 236, 356). 



A characteristic type of cytolysis in Paramecium has been described 

 by Hertel (142) in an interesting early paper. Other descriptions of 

 cytolysis in Paramecium include Thomaschewski (359), Cernovodeanu 

 and Henri (57), Bovie (33, 34), Burge (53), Bovie and Daland (38), 

 Rentschler (313), and Troisi (360). These different authors stressed 

 various morphological appearances, but the picture as a whole is quite 

 consistent. Hertel noted especially the lifting off of the pellicle here and 

 there on the surface of the animal and its frequent rupture. This may 

 be related to the liquefaction of the cortical protoplasm of Amoeba, as 

 described by Heilbrunn and Daugherty (137). 



In review, it may be stated with some degree of confidence that 

 ultra-violet rays cause first a liquefaction of the main mass of the proto- 

 plasm and then a pronounced stiffening. The liquefaction of the cell 



