THE INFLUENCE OF TEMPERATURE 



If the temperature 

 is more rapidly raised, 

 the velocity of streaming 

 goes on increasing up 

 to over 45 C., becomes 

 irregular and jerky at 

 55 C., and ceases entire- 

 ly after five minutes at 

 60 C., but even then the 

 power of recovery is fre- 

 quently retained. 



Whenever stream- 

 ing is stopped by high 

 temperatures, the chloro- 

 plastids tend to ball to- 

 gether more or less com- 

 pletely, slowly spreading 

 out again when stream- 

 ing is resumed. Irregu- 

 lar twitching movements 

 first occur, and in some 

 cases the chloroplastids 

 appear to be jerked for- 

 wards and then slightly 

 back wards with an elastic 

 recoil, just as if the proto- 

 plasm had undergone 

 partial coagulation and 

 contained highly viscous 

 threads of myosin-like 

 proteids. 



Similar results were 

 given by Elodea cana- 

 densis. 



If actively stream- 

 ing cells are raised 4 C. 

 per minute from 20 C. 

 upwards, streaming is 

 slower at 40 C. than at 

 20 C. (18:34), but only 

 ceases when 60 C. is 

 reached and the cells 

 are fatally affected. If 



