258 



follows, it is then iialur.-il to lliiiik tlint dcalh results 

 from the inability to jjroduec eiion^li ciicrnv to compen- 

 sate for that whieli is withdi-awii. 



This theory has been aj)|)rKMl to cold -hlooch-d animals 

 which, it has been claimed for a lon<i- time, succnmb to 

 cold when they lose more heat than they can supply. As 

 a typical representative of the many authors who held 

 this view, during the last century, we shall mention Pla- 

 teau (1872). He claims to have observed that aquatic 

 arthropoda immersed in freezing- watei- die when they 

 are caught in the ice in such a way that they cannot make 

 any more movement and consequently cannot produce 

 any more heat. 



While the production of energy by cold-])looded ani- 

 mals seems to have been universally recognized by the 

 earliest physiologists, the production of heat by plants 

 was still a subject of controversy a century ago. Goep- 

 pert, in 1830, in his book entitled: "Ueber die Warme- 

 Entwicklung in den Pflanzen, deren Gefrieren und die 

 Schutzmittel gegen dasselbe", states (p. 228) that the 

 plants "do not possess the ability to produce their own 

 heat" ("eigene Warme"). His conclusion is that, since 

 plants cannot resist cold by producing heat themselves 

 i}or by receiving heat from the ground, "their vital force 

 ("Lebenskraft") is the first and most important and per- 

 haps the only source from which the resistance to the 

 harmful influence of cold arises" (p. 225). Each species 

 would possess a certain vital force which requires a given 

 withdrawal of energy for its destruction. 



It is interesting to mention, in connection with this con- 

 cept of specific energy content of living matter, an idea 

 which was quite generally accepted during the last cen- 

 tury, namely, that freezing could not take place in living 

 plants and animals, but that life had to be destroyed be- 

 fore congelation could occur. The destruction of life, it 

 was thought, was caused by cold ahme, that is, by the 

 withdrawal of energy. 



