Evolution of Animals 417 



in the Haemoflagellata and in the Infusoria the nuclear chro- 

 matin early separated after fertilization into a trophonuclear 

 (for the former) and meganuclear (for the latter) constituent, 

 also into a kinetonuclear (for the fonner) and micronuclear 

 (for the latter) mass. The trophonuclear and meganuclear 

 bodies seem to correspond largely in energizing and organi- 

 zation action to the cognitic nuclear substance of plant and 

 simpler animal cells. The kinetonuclear and micronuclear 

 bodies seem to be greatly more complex, energized, and heredi- 

 tarily important, as if commencing centers or substances for 

 cogitic energizing action and reaction. 



It would be of special interest therefore to learn whether, 

 in the formation of reproductive cells and of ganglion cells 

 in rotiferan embryos, there is not given off to or accumulated 

 in these a more complex super-chromatin Nissl substance, 

 or kinetonuclear substance, that becomes associated with 

 flows and condensations of cogitic energy. The future will 

 alone determine whether such a possibility exists. 



So wliile we would view the coelenterate and ecliinoderm 

 stocks as side lines of evolutionary advance, which both de- 

 velop a nervous system that is typical for them, it is to the 

 Rotifera and progressively derived groups therefrom that we 

 would look for the direct line of invertebrate- vertebrate ascent. 

 This then is our immediate quest. 



But, in comparing these and in considering the possible 

 origin of higher invertebrates and of vertebrates, we are brought 

 face to face with several well known circumstances. First: 

 If we regard the cambrian epoch as that during which life 

 can be traced directly in its earliest fossil remains, and glance 

 backward to the archsean as well as forward through all suc- 

 ceeding epochs, it seems as if life had comparatively suddenly 

 appeared in telescoped complexity and variety. For, apart 

 from readily obliterated plant life and from simple soft animal 

 organisms that may equally have been obliterated, we are 

 suddenly confronted with elaborate rei)resentatives of nearly 

 every invertebrate grouj), while, in the ordovician formation 

 above, remains of insects, scorjnons, and fishes tell us that 



14 



