lo Evolution and Distribution of Fishes 



and more perfect heritage from simpler inorganic colloid 

 substances or bodies. 



Each of these functions also might vary in activity, in 

 exhibition, in relation the one to the other, or to agencies 

 around, according to the kind and strength of environal 

 stimuli that the organism might be exposed to. This will 

 be seen to be strikingly true in the history of many groups 

 of fishes at various stages in their existence. 



But an examination of the simplest plant and animal 

 organisms now living tends to show that the latter branched 

 off from the former as a group that gradually became 

 adapted to active motion, or in other words which showed 

 increasingly active and delicate response to environal stim- 

 uli; also that they came to depend more and more on the 

 catching and absorption of other living organic bodies, that 

 is they became epibiotic in their nutritive relations. Soon 

 however the common stock of simpler plants and of the 

 most primitive animals, that had branched off from them 

 in their higher members, became increasingly responsive 

 to environal stimuli, and so a still higher and more perfect 

 quality of energy condensed from the biotic, and such the 

 writer has termed the cognitic. This became associated 

 with a correspondingly complex exhibition of, and linkage 

 of, matter to form chromatin substance. And the aggre- 

 gation of this chromatin into a definite mass gave rise to 

 that highly energized body of each cell or protoplasmic 

 mass that we call the nucleus. So the biotic energy of each 

 cell protoplasm, and the more condensed cognitic energy 

 of each cell nucleus conferred first the vegetative (or liv- 

 ing) and later the actively irrito-responsive qualities on' 

 each organism that was made up of an aggregation of 

 many such cells. 



Thus each organism, by activity of the protoplasm, be- 

 came slowly adapted to or modified for the appropriate 

 chemical substances that might act as food or as promoters 

 of respiratory change. But in virtue of the highly sensitive 

 and responsive chromatin substance of the nucleus, increas- 

 ingly active response was made to heat, light, moisture 

 conditions, gravity and other environal exhibitions of 

 energy. 



