IOWA ACADEMY OP SCIENCES. 
35 
In other words: 
One is full and dying of plethora. 
The other is hungry and dying of excessive expenditure of 
energy. 
It would evidently be a good thing for them to pool their 
issues. 
This is effected by the process of conjugation, whereby: 
First . — The small, active, katabolic cell imparts its energy 
(kinetic) to the large passive cell, and that energy expresses 
itself in cell division. 
Second . — The large, passive, anabolic cell imparts to the 
daughter cells its anabolic propensities which express them- 
selves in growth. 
In other words: 
The anabolic cell receives the impetus necessary to cell 
division or fission, and the katabolic cell receives nourishment 
and the tendency to grow. 
What brings them together? 
Hunger, or its equivalent. 
Hunger is a fundamental property of all things that need 
nourishment. 
It is therefore a property of katabolic cells. The small, 
active cells need nourishment. The large, anabolic cells are 
packed full of nourishment. 
Example — Acinetan. 
An intensification of this process would be brought about in 
time by natural selection and would result in multiple fission, 
external and internal, which is the highest expression of sex 
found among the Protozoa. 
SEX IN THE METAZOA. 
Hydroid as a Type . — The male cells originate from amoeboid 
endodermal cells which differentiate along the line of katabo- 
iism. They divide repeatedly and eventually become the 
smallest and most active cells in the colony. The female cells 
originate from amoeboid endodermal cells which differentiate 
along the line of anabolism. They grow excessively and 
become passive and circular in outline. They eventually 
become the largest and least active cells in the body. 
Tnese two cells unite, or the smaller seeks the larger and is 
absorbed in it. As a result: 
