H8 BIOLOGY. [Book ii. 



an almost uniform exterior temperatm-e.^ On the contrary, birds, 

 whose nutritive movement is intense and rapid, succusBab very 

 quickly. One day of abstinence kills a spaiTOw, thi-ee days a 

 thrush, &c. The same law is verified in the, same animal organ- 

 ism, according to the various; ages. Thus,. in middle life,, man can 

 resist complete abstinence for one or two weeks. The child 

 succumbs sooner, and the old man much later. 



Everything which retards .the quickness of the nutritive 

 exchanges helps to support abstinence; for example, repose in 

 bed, sleep, and the. substances which provoke it. 



.Without having for the animal the .primordial impoi-tance 

 which it has for the plant, solar light is nevertheless a powerful 

 excitative of life in the animal .kingdom also. Moreover, absti- 

 nence is better supported in darkness. Eight miners shut up 

 for thirty+six hours in la coal-pit without food ^aid they had 

 not suffered from hunger. 



Nevertheless, in all animals death is sooner .or -later the 

 result of abstinence, and in all, it takes place when the organism 

 has lost apart'of itsweight, always perceptibly the same for all 

 the species. ; If the animals known as cold-blooded Jive mueh 

 longer than others, it is only because their diurnal loss is normally , 

 much less. They expend less, aiid consequently their capital is 

 not so soon exhausted. 



^ 01. Bern&j;d, Legans mr les Propri^i^s desTisms, Vimnt^, V- ^?- 



