•23 



the bodies of the organisms contracted, ami then their movements which 

 had hitherto been active became slower and slower until they ceased 

 entirely. In a few hours, however, the contraction of their bodies gradually 

 disappeared and they recovered their normal condition, accommodation 

 to the new medium now beginning to take place. Similarly, Fischer 1 ' 

 found that 10 — 30?£ cane-sugar, which caused strong plasmolysis on 

 Spirillum, stopped its movement, Ewart-' also observed that Bacterium 

 Termo, which moved actively in lQo/ cane-sugar or 5o/ grape-sugar, 

 lost its activity in 2Qo/ cane-sugar or 10^ grape-sugar, and finally came 

 to rest in 30% cane-sugar or 20^ grape-sugar. 



The higher the concentration of the solutions, the more difficult the 

 accommodation of infusoria to them became, and when it took place the 

 vacuoles or the corpuscles in the bodies of the organisms remained 

 increased in size as well as in number while their bodies became much 

 thicker, with outlines presenting a more or less rounded appearance. 



Of the five external media I used the sugar-solutions proved to 

 be the best adapted to the organisms, the highest degree of adaptation 

 being possessed by milk-sugar, then followed cane-sugar and next 

 grape-sugar. Glycerin was found to be better adapted than common salt. 



It is evident that the action of the above substances is not due to 

 the degree of their concentration but to their chemical nature ; for the 

 solutions which were in isotonic concentration did not have the same 

 effect upon the organisms. Thus, in the cultures of Colpidium colpoda, 

 for example, 8o/ cane-sugar, which is isotonic with 8'4^ milk-sugar, 

 4-2^ grape-sugar, 2-2o/ glycerin and 0-9% common salt, formed the 

 highest limit, together with \0% milk-sugar, 7% grape-sugar, b% 

 glycerin and \o/ common salt, so that the limits in the latter case were 

 generally found to be far higher than those in the former, except with 

 common salt where, on the contrary, the adaptation of the organism 

 was much lower. A similar observation was made by Stange, S) who 

 found that isotonic solutions caused various growth-rates in the bodies 

 of plants. 



l > A. Fischer. Untersuchungen fiber Bakterien. Pringsh. Jahrb. 1895- Bd. XXVII. pp. 



39-40. 



21 A. j. Ewnrt. On Asstmilatory Inhibition in Plants. The Journal of the Linnean 

 Society. 1896. Vol. XXXI, No. 217. p. 434. 

 8 > B. Stance, fa. Nr# 2 2. p. 364. 



