298 BIOLOGY. [BOOK in. 



neither law nor rule when the course of life is abandoned to the 

 hazard of events, as always happens. A priori, it is surely not 

 impossible, an organised being given, to maintain indefinitely in 

 it the tide of life at a constant watermark, and it seems to us 

 that science is now sufficiently armed to attack boldly this 

 great problem. It would be necessary to bring observation and 

 experiment to bear first of all upon very simple organisms, whose 

 normal life is very short. We should commence by determining 

 the average duration of that life when the organism is abandoned 

 to itself. Then, being guided as much as possible by scientific 

 facts already acquired, we should vary in a hundred ways the 

 light, the temperature, the alimentation, the composition of the 

 atmosphere, &c., &c., noting carefully the effect of each new 

 factor, of each variation of medium. 



Furthermore, we should scrutinise the conditions of life and 

 of organism in the species remarkable for their longevity, then 

 in individuals whose duration is exceptionally long. Evidently 

 the investigation itself would suggest new modes of research. 

 We should fail, or we should succeed. In any case, something 

 useful would result from this labour. 



In fact, biology will not be a complete science till it has 

 learned to comprehend life. A man of science, who cannot 

 without injustice be accused of philosophical temerity, has 

 already proclaimed this : " The physico-chemical actions, which 

 manifest and regulate the phenomena belonging to living beings, 

 are included in the ordinary laws of general physics and 

 chemistry" (p. 4). 



" . . . . There is only one system of mechanical philosophy, 

 only one system of physics and of chemistry, which comprehend in 

 their laws all the phenomena which take place around us, either 

 in machines living or machines dead. Under the physico- 

 mechanical relation, life is only a modality of the general 

 phenomena of nature ; it engenders nothing, it borrows its forces 

 from the outer world, and only varies its manifestations in 

 thousands and thousands of ways " (p^ 135). 



