46 _ Vitality and Organization of Protoplasm. 



solid imrticles of undigestible nutritive material;, and particles derived" 

 from deteriorated protoplasm, are eliminated by being bodily crushed 

 out of the vital cycle. 



Depuration brings the protoplasmic individual into a third direct re- 

 lation of interaction with the medium, and especially with its atmos- 

 pheric oxygen. 



The living substance stands thus in three different direct and vital 

 modes of dependence upon its medium. Its vitality is conditioned and 

 actuated by the three different processes of interaction which arise from 

 these three modes of dependence. First, the stimulating process which 

 specifically incites the ectodermic or dynamical functions; second, the 

 nutritive process which furnishes the complemental material for rein- 

 tegration; and third, the depurative process which necessitates the ab- 

 sorption of atmospheric oxygen. These vitally indispensable modes of 

 interaction presuppose an intimately pre-established harmony between 



I every structure and function of the organism and the conditioning and 

 actuating factors of the medium. This proves that fundamental adap- 

 tation of the organism to its medium is coeval with life itself at every 

 stage of its evolution, as Gustav Wolff has pointed out in his masterly 

 polemic against adaptation by means of natural selection. 



GROWTH AXD REPKODUCTIOX. 



The general conditions which give rise and which sustain the vital 

 activity of the substance composing living beings, involving motility, 

 nutrition and depuration, have in their essential characteristics been 

 considered. There remains unexplained the growth and the reproduc- 

 tion of organic individuals. 



After having gained an insight into the process of assimilation, indis- 

 pansably connected with reintegration of the living substance, that 

 which essentially constitutes organic growth becomes almost self-evident. 

 Growth, when manifested to its full extent, consists evidently in the 



(power of a fragment of the living substance derived from an adult 

 organism to reintegrate itself, so as to reproduce the complete adult 

 form. In ordinary functional disintegration the identity of the adult 

 organism is quite obviously restored by means of complemental reinte- 

 gration through assimilation of nutritive material. The deeper the dis- 

 intregation penetrates, the larger the specific chemical gap to be com- 

 plementally filled. The disintegrated living substance forms thus a 

 more or less disequilibrated chemical fragment of its former self, en- 

 dowed with the power of reintegrating or regenerating under suitable 

 conditions. This power of fragments of organism to reconstitute the 

 entire individual is most strikingly evidenced l)y parts of the living sub- 

 stance artifically severed from organic individuals. Trembly's experi- 

 ments on the regenerative power of sweet water jiolyps, published as 

 early as 1714, and Reaumur's experiments chiefly on earthworms, pub- 

 lished in 1742, which experiments were repeated and extended by other 

 investigators, remained more a source of wonderment than of scientific 



