332 
The Ohio Naturalist. 
[Vol. V, No. 7, 
that the cell wall was developed as a protective covering. When 
these primitive cells were in process of division there could be an 
interchange of food from the one to the other so long as the 
protoplasmic connection was not completely cut. After complete 
separation the two daughter cells, still lying in contact, could 
exchange food by osmosis, the one having a less amount of food 
taking from the one having a greater supply. After the two cells 
had separated they might exchange food in the same way on 
coming in contact for any length of time by accident. In this 
way sexual evolution may have had its beginning as well as 
parasitism in all of its forms. After the process of temporary or 
permanent conjugation was once established it would be of 
advantage to the species under many adverse conditions. A 
set of starved or weak organisms meeting with a well nourished 
lot could conjugate either temporarily or permanently, greatly 
to their advantage, without doing the stronger individuals any 
special harm. Such is apparently the behavior of various lower 
organisms at the present time. Furthermore a swarm of uni- 
cellular organisms or zoospores in a given area is, by conjuga- 
tion, reduced to just half the previous number. The mere 
reduction in the number of units might be a very important fac- 
tor in the immediate w^elfare of the species especially when the 
further dela}^ of reproduction incident to the process of conjuga- 
tion is taken into account. In many of the lower plants the 
arrival of adverse conditions is the stimulus to the formation of 
resting zygospores or oospore.s by means of which the organism 
is |)reserved until a more favorable environment is again at hand. 
Rejuvenescence, using the term in its broadest sense, seems at 
least a very plausible cause of the origin of sexuality if it is once 
admitted that conjugation is not one o' the fundamental prop- 
erties of the protoplasm of primordial 'organisms. Other means 
of rejuvenescence should serve the same purpose as the stimulus 
and reaction which one mass of protoplasm must exert on 
another during conjugation, leaving out of consideration the fact 
of the reduced space occupied by the two united organisms and 
consequently the less surface in contact with the surrounding 
medium. A tree may be rejuvenated by placing a fertilizer 
about its roots. So organisms which naturally rejuvenate only 
through conjugation may be rejuvenated through a favorable 
change of food or other factors of environment, thus actually 
delaying the necessity of a conjugation for a long period of time. 
Whether conjugation was long or short in its evolution is of 
no special importance in the discussion of the remaining ques- 
tions formulated above. The first time that nucleated cells con- 
jugated so completely as to act in cell division as a single cell a 
disturbance was present not operative in the race previously. 
The two nuclei having fused contained twice the amount of 
