206 THE INDUCTIONS OF BIOLOGY. 



multiplication — from cell-reproduction to cell-generation. 

 The phenomena are so numerous and so varied that a large 

 part of them must be passed over. Conjugation among the 

 Protophyta and Protozoa, beginning with cases in which there 

 is a mingling of the contents of two cells in no visible 

 respect different from one another, and developing into a great 

 variety of processes in which they differ, must be left aside, 

 and attention limited to the terminal process of fertilization 

 as displayed in higher types of organisms. 



Before fertilization there occurs in the ovum an incidental 

 process of a strange kind — " strange " because it is a col- 

 lateral change taking no part in subsequent changes. I 

 refer to the production and extrusion of the " polar bodies." 

 It is recognized that the formation of each is analogous to 

 cell-formation in general; though process and product are 

 both dwarfed. Apart from any ascribed meaning, the fact 

 itself is clear. There is an abortive cell-formation. Abor- 

 tiveness is seen firstly in the diminutive size of the separated 

 body or cell, and secondly in the deficient number of its 

 chromosomes : a corresponding deficiency being displayed in 

 the group of chromosomes remaining in the Qgg — remaining, 

 that is (on the hypothesis here to be suggested), in the 

 sister-cell, supposing the polar body to be an aborted cell. 

 It is currently assumed that the end to be achieved by thus 

 extruding part of the chromosomes, is to reduce the re- 

 mainder to half the number characterizing the species; so 

 that when, to this group in the germ-cell, the sperm-cell 

 brings a similarly-reduced group, union of the two shall 

 bring the chromosomes to the normal number. I venture to 

 suggest another interpretation. In doing this, however, I must 

 forestall a conclusion contained in the next chapter; namely, 

 the conclusion that gamogenesis begins when agamogenesis 

 is being arrested by unfavourable conditions, and that the 

 failing agamogenesis initiates the gamogenesis. Of numerous 

 illustrations to be presently given I will, to make clear the 

 conception, name only one — the formation of fructifying 



