THE EFFECTS OF HEAT AND RADIANT ENERGY III 



cal complications, the lowering of temperature does not seem to bring 

 about irreversible changes in the condition of protoplasm, which are 

 incompatible with life. This seems to be in harmony with the fact 

 that living matter contains no colloidal solutions which are transformed 

 into irreversible gels by cooling. Gelations which are brought about 

 by cooling seem ta be, in general, reversible processes, e.g. the gelation 

 of gelatine. 



Experiments made recently by Pictet and others show that various 

 cold-blooded animals and bacteria may be cooled to very low tem- 

 peratures without being killed. Many, possibly most, warm-blooded 

 animals seem, however, to behave differently. If their blood is cooled 

 for some time to a temperature of 15 C. or below, they cannot again 

 recover. If this fact which is generally stated is correct, it shows that 

 in the warm-blooded animals a reversible, fatal change occurs at 

 such a lowering of their temperature, although we have not the slight- 

 est conception which substance or variable is responsible for this re- 

 sult. It is interesting that, according to Setchell, the Cyanophycece of 

 the hot springs also die when suddenly brought into water whose 

 temperature is below 40. It is possible that we are dealing in this 

 case also with some secondary effect connected with the lowering of 

 temperature. 



The variables thus far mentioned do not yet exhaust the range of 

 possibilities in which temperature influences life phenomena. The 

 coefficient of partition of one substance between two others may vary 

 with the temperature. This is the case, e.g. for the coefficient of par- 

 tition of chloralhydrate between oil and water. This coefficient in- 

 creases with the temperature, which means that with an increasing 

 temperature more chloralhydrate will leave the watery liquids of the 

 body and go into the tissues which are rich in fat, e.g. nervous elements. 

 In consequence of this fact a frog which is poisoned with chloralhy- 

 drate at room temperature may become normal again upon cooling, 

 as chloralhydrate must in this case go from the nervous elements into 

 the watery liquids of the body. The following fact belongs possibly 

 in the same category. It is known that decapitated frogs show an 

 increase in irritability when kept for some time on ice. If the reaction 

 velocity were decisive for the reflex irritability, it should be expected 

 that, with an increase in temperature, the irritability would increase. 

 Could it be possible that in this case the coefficient of partition of some 

 toxic or inhibiting substance formed in the body varies in the same 

 sense with the temperature, as in the case of chloralhydrate? If this 

 were the case the fact might become intelligible that with decrease in 

 temperature the reflex irritability is increased. 



