IOWA ACADEMY OF 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 groivth. 



la 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. 



Eydroid 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. 



These two cells unite, or the smaller seeks the larger and is 

 absorbed in it. As a result: 



