106 



THE INFLITENCB OF INANIMATE SURROUNDINGS. 



freezing point is reached, while some animals can endure even 

 to be actually frozen up without being killed, their vital powers 

 merely becoming latent. Sometimes the effect of the reduced 

 temperature induces modification of the functions only, some- 

 times it leads to changes in organic structure. Unfortunately 



Intervals bettveen two Contractions. 



In See. 2 4 6 8 10 12 14 16 18 20 22 21 26 28 30 32 34 degrees centigrade. 



Fig. 27. — The mean thermal curves detected by Rossbach for the contractile vesicle of 

 Infusoria. I. Yot Euplotes Charon. 11. Vor Siylonychia pmluktta. III. ¥oi Chilodm 

 cucullulus. The animals are shown in fig. 28. , 



very few experiments on individual cases have been made 

 which elucidate this branch of the subject, but we will investi- 

 gate these more closely. A reduction of temperature which 

 never falls so low as the freezing point of fresh water may still, 

 under some circumstances, lead to the suspension of various 



