Origin of Sexuality 245 



with primitive asexual forms, and to work upward to others 

 that become gradually more complex, the student is suddenly 

 plunged into the most complicated questions of inheritance 

 amongst highest plants and animals. The aim in this chapter 

 will be to trace evolutionary progress step by step, so far as 

 possible with the fragmentary plant and animal record of the 

 present day. But, for a correct understanding of the phe- 

 nomena of sexuality, it is absolutely necessary that we approach 

 the subject by the pathway of cell-division, as the succeeding 

 context will demonstrate. 



In such Acaryota as Chroococcus^ Sarcina, many of the 

 simple bacteria, and in Proteomyxa, each organism is a simple 

 cell that shows no apparent trace of nuclein or nuclear rudi- 

 ment, and that multiplies by simple division of the proto- 

 plasm. But as already emphasized (p. 98) such a process is 

 not to be regarded as a mere haphazard separation into equal 

 or unequal halves of a homogeneous substance. Every new 

 fact gained adds to the view that the protoplasm is an extremely 

 complicated chemical foam that is made up of very definitely 

 related compounds arranged into definite lines, groups, or 

 areas of complex molecules, that are traversed by and con- 

 stantly altered by definite currents of energy. Slow responses 

 also are made to environal stimuli, and in the process food 

 and oxygen are absorbed, which in time set up intrinsic meta- 

 bolic and stimulatory changes. 



But, in simple plants like Chroococcus, Aphanocapsa, and 

 others, there seems to be little if any polarity, so that succes- 

 sive divisions are successively at right angles to each other, 

 as if the whole mass were a uniform — even though molec- 

 ularly complex — substance, that in attaining a certain size 

 begins — from surface-tension, gravity, and other relations — 

 to fall into halves, each of which again may grow in size. But, 

 even in dividing along definite rectangular planes, we have 

 evidence that definite lines of energy-flow are traversing the 

 protoplasmic substance, and are transi)orting materials to 

 localized areas in exact manner. IIow then can such phe- 

 nomena be led up to, from conditions that are purely inorganic.'^ 



