256 LAMARCK, HIS LIFE AND WORK 



To make sure whether the exercise of life tends to 

 extend and develop the organization, it suffices to con- 

 sider the state of the organs of any animal which has 

 just been born, and to compare them in this condition 

 with what they are when the animal has attained the 

 period when its organs cease to receive any new 

 development. Then we will see on what this organic 

 law is based, which I have published in my Recherches 

 sur les Corps vivans (p. 8), i.e., that — 



" ' The special property of movement of fluids in 

 the supple parts of the living body which contain 

 them is to open {frayer) there routes, places of 

 deposit and tissues ; to create there canals, and con- 

 sequently different organs ; to cause these canals and 

 these organs to vary there by reason of the diversity 

 both of the movements as well as the nature of the 

 fluids which occur there ; finally to enlarge, to elon- 

 gate, to divide and to gradually strengthen {affermir) 

 these canals and their organs by the matters which 

 are formed in the fluids in motion, which incessantly 

 separate themselves, and a part of which is assimilated 

 and united with organs while the rest is rejected.' 



" Secondly, the continual employment of an organ, 

 especially if it is strongly exercised, strengthens this 

 organ, develops it, increases its dimensions, enlarges 

 and extends its faculties. 



" This second law of effects of exercise of life has 

 been understood for a long time by those observers 

 who have paid attention to the phenomena of organ- 

 ization. 



" Indeed, we know that all the time that an organ, 

 or a system of organs, is rigorously exercised through- 

 out a long time, not only its power, and the parts 

 which form it, grow and strengthen themselves, but 

 there are proofs that this organ, or system of organs, 

 at that time attracts to itself the principal active 

 forces of the life of the individual, because it be- 

 comes the cause which, under these conditions, 



