GENESIS. 295 



state of general equilibrium in such gamogcnetic individuals, 

 is accompanied by an approach towards molecular equilibrium 

 in them; and that the need for this union of sperm-cell and 

 germ-cell is the need for overthrowing this equilibrium, and 

 re-establishing active molecular change in the detached germ 

 a result probably effected by mixing the slightly different 

 physiological units of slightly different individuals. The 

 several arguments which support this view, cannot be satis- 

 factorily set forth until after the topics of Heredity and 

 Variation have been dealt with. Leaving it for the present, 

 I propose hereafter to re-consider it in connexion with sundry 

 others raised by the phenomena of Genesis. 



But before ending the chapter, it may be well to note the 

 relations between these different modes of multiplication, and 

 the conditions of existence under which they are respectively 

 habitual. While the explanation of the teleologist is untru-e, 

 it is often an obverse to the truth; for though, on the hypo- 

 thesis of Evolution, it is clear that things are not arranged 

 thus or thus for the securing of special ends, it -is also clear 

 that arrangements which do secure these special ends tend 

 to establish themselves are established by their fulfilment 

 of these ends. Besides insuring a structural fitness between 

 each kind of organism and its circumstances, the working 

 of " natural selection " also insures a fitness between the mode 

 and rate of multiplication of each kind of organism and 

 its circumstances. We may, therefore, without any teleo- 

 logical implication, consider the fitness of homogenesis and 

 heterogenesis to the needs of the different classes of organisms 

 which exhibit them. 



Heterogenesis prevails among organisms of which the food, 

 though abundant compared with their expenditure, is dis- 

 persed in such a way that it cannot be appropriated in a 

 wholesale manner. Protophyta, subsisting on diffused gases 

 and decaying organic matter in a state of minute subdivision, 

 and Protozoa, to which food comes in the shape of extremely 

 small floating particles, are enabled, by their rapid agamo- 



