CHAP, iv.] OX THE GENERAL CONDITIONS OF GROWTH. 299 



"By modifying the inner nutritive and evolutive mediums, 

 and by taking the organised matter in some degree from its 

 birth, we may hope to change its evolutive direction, and conse- 

 quently its final organic expression. In a word, I think that we 

 can produce scientifically new organised species in the same way 

 that we create new mineral species, that is to say, that we can 

 cause the appearance of organised forms, which exist virtually in 

 the organogenic laws, but which nature has never yet realised" 

 (p. 113). 



" Life is extinguished, and natural death takes place, only 

 because the production of the plastic element stops, and because 

 then the passive tissues become impregnated and incrusted with 

 mineral and other matters, which cramp their functions, and 

 lessen more and more the nutrition, or the genesic formation of 

 the active histological elements" (p. 126). 



" To sum up, what the physiologist wants, is to be able experi- 

 mentally to direct the evolutive phenomena in such a way as to 

 modify the nutrition of the organised matter, in order thereby 

 to change more or less the duration, the intensity, or even the 

 nature of its vital properties" (p. 129). 



" Up to the present time, physiology has been struggling with 

 transitory ideas, which will disappear in proportion as science 

 advances. With regard to physiology, we are just at the point 

 where alchemy was before the foundation of chemistry. The 

 views which may now be expressed with relation to the modes 

 of action of the physiological experimentalist will only be the 

 result of gropings more or less vague ; but, nevertheless, these 

 acts will not be less positive, and the scientific principle of 

 general physiology cannot remain doubtful or uncertain. Phy- 

 siology, like all the terrestrial sciences whose phenomena are 

 within our reach, must become in time an active experimental 

 science upon the phenomena of life" (p. 219). 



" When the progress of general physiology shall have shown 

 the experimentalist the special organic elements upon which ho 

 acts, and he shall have learned to master the conditions of their 



