eS ern 
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Spe ect Se at epee age hoa a E T 
1885.] ° Comparative Phystology and Psychology. 17 
assimilable phosphates. The resulting nervous system became 
more and more definite in tract formation as motions became 
more and more definite between parts. These nerve granules 
had a molecular mode of action altogether different from any- 
thing experienced before by the animal. In higher forms the 
cell substance, which had the particular ability to excrete or 
secrete it (relative terms), formed along the area of the plexus and 
tracts, next an encapsulating membrane formed about it, in obedi- 
ence to ordinary physiological and pathological processes that an 
intermediary substance will be attracted and form around tissues 
or even foreign substances as a resultant of the mode of opera- 
tion of the two tissues. In due time areas of nerve granule gen- 
eration find in itself small plexiform areas which are turning 
points of direction for the molecular nerve discharge, and by en- 
capsulating these the nerve cell is formed, which I regard as hav- 
ing no other functions than a histogenetic one aside from the 
molecular impacts passing through it. From protoplasm exuding 
the nerve granules the nerve cells develop to that office; from in- 
different tissue forming cartilage, some of the latter form osteal 
cells. 
A plexiform rudimentary nervous system conveys irritations 
over the body. When the discharges become definite the linear ar- 
rangement appears as in the ascidian embryo, the head end devel- 
oping through tactile and rudimentary sense organs determining 
there with frontal impact of environment. Most influences act- 
ing to excite the squirt or vermicular motions from mouth to 
anus, a method of locomotion and ingestion at the same time. 
It is easy to see how the mechanical perforation of a ccelenter- 
ate sac caused the enteron to be completed, but the origin of the 
circulatory system is not so evident. The enteroccele is in direct 
communication with the enteron in ccelenterates and the fluid 
it contains, as Huxley says, “ represents blood,” it is nutrient ; the 
lacunz of some worms are the next step toward a blood vascu- 
lar system. The pseudo-hemal system of the Annelida contains 
a substance resembling hemoglobin, and with these facts before 
us we may construct the vascular system and its workings in 
some such way this: Ccelom, a receptacle for a fluid containing , 
nutrient matter which had strained through the endodermal cells 
and through interstices between them. Next the appearance of 
hzmoglobin or its —— in the ceelom. The eel proper- 
VOL. XIX.—NO. 
