31 



complete disintegration of the organism. In no ease did 

 a paramaecium ever survive the freezing of its medium. 



Fol (1884) isolated living ciliates from dried soil frozen 

 at about -100°. 



Taylor and Strickland (1936) found that immersion in 

 liquid air for 13 i hours does not affect the viability of 

 air-dried cysts of Colpoda cucullus. In another experi- 

 ment these authors obtained some excystment (percentage 

 unknown) from cysts first subjected to a vacuum of about 

 10 ' mm. of mercury for 2 or 3 days, thereupon exposed 

 to liquid air temperatures for 12| days, and then warmed 

 to room temperature within 2 minutes. 



Becquerel (1936) ioi\i\d\iy\i\g Paramaecium hursaria in 

 dried soil kept for 7? hours at a temperature of about 

 2°K. 



3. Flagellate,^. Mainx {Arch. f. Protisten'k., 60, 387, 

 1928) did not find any evidence in favor of the belief that 

 Euglena can withstand freezing. He observed that par- 

 tially or completely frozen cultures of Euglena gracilis, 

 E. viridis and E. deses gave rise to very few living forms, 

 and to these only if cysts were present previously. 



According to Jahn (1933), when Euglena cultures were 

 kept in the frozen state, at -4°, for 1 hour, most of the 

 organisms, but not all, were killed. A temperature of 

 -0.2° maintained for the same time, without freezing of 

 the medium, showed no harmful effect. 



On the other hand, Giinther (Arch. /. Protistenlx., 60, 

 556, 1928) reported that he observed a specimen of 

 Euglena terricola which liad been frozen while in the 

 process of mitosis and which completed its division, on 

 the microscope, in a normal manner when the ice melted, 

 after having been congealed for 8 days at -12°. 



Klebs {Ztschr. f. iviss. Zool., 55, 265, 1893) observed 

 that Euglena, in the free s^\^mming state, was not killed 

 by repeated freezing. 



Trypanosoma gambiense, according to Gaylord (1908) 

 can resist being immersed in liquid air for 20 minutes, but 

 is killed after 40 minutes. 



