EFFECTS ON THE PROTOZOA 



23 



die during the experiment and their disintegrated corpses, or more likely the 

 bacteria which thrive thereupon, serve as food to prolong the life of the sur- 

 vivors. Lipska sought to avoid these difficulties by improvements in the experi- 

 mental technique: (1) by repeated washings of the paramecia in boiled water at 

 the beginning; and (2) by isolation of individuals, each in sterile water in a 

 capillary glass tube two or three cm. in length, kept horizontally in a moist 

 chamber. About 3,500 individuals were so observed, and in 350 cases the para- 



ect: 



end.— 



f.v. Is 



I — cr. 



Figs, i to 6. — Paramecia in various stages of inanition. Figs, i to 5 from Lipska ('10); 

 Fig. 6 from Wallengren ('02). Magnification about X400. b.g., buccal groove; c, cilia; cr, 

 excretion crystals; d.v., degeneration vacuoles; ect., ectoplasm; end., endoplasm;/., fold in body; 

 f.v., food vacuoles; TV, macronucleus; n, micronucleus. 



Fig. 1. — : Normal Paramecium caudalum of average dimensions. 



Fig. 2. — Paramecium after six days of inanition. The macronucleus (TV) is greatly 

 enlarged, occupying the posterior half of the pear-shaped body. 



Fig. 3. — Paramecium after seven days of inanition. The macronucleus (TV) is elongated; 

 micronucleus (w) emigrated to posterior end of body. Two depressions are visible on the 

 body, separated by a thick ridge or fold (/). 



mecia were finally fixed, stained and mounted for more detailed microscopic 

 study. The results, in comparison with those of her predecessors, will be sum- 

 marized briefly (Figs. 1 to 5). 



The average duration of life under such conditions was found by Lipska to be 

 only five to seven days. The time varies according to circumstances, however. 

 The (exhausted?) individuals starved immediately after conjugation survive 

 only about three days. A few individuals, especially those containing symbiotic 

 green algae, may survive ten or twelve days; and those previously hypernour- 

 ished may survive even fifteen to twenty days. The higher averages of pre- 

 vious observers represent merely the few survivors of an incomplete inanition. 



