3-20 THE DOCTRINE OF DESCENT. 



natural extinction of the individual ; a fourth portion might 

 possess the properties requisite for self-preservation as well as for 

 the preservation of the genus, yet lacked that peculiar tendency 

 to vary (Philosophic des Unbewussten, p. 591), or at least that ten^ 

 dency to vary in the particular direction which was alone capable 

 of leading to development into higher forms ; and finally a fifth 

 portion possessed this property in addition to the others. It is the 

 progeny of the fourth and fifth classes of our division which still 

 populates the ocean and the earth.* From which species of 

 JMonera proceeded the advanced development of the Infusoria ; 

 whether from one still living or from an extinct species we do not 

 know as yet ; but this much we may accept as certain, that the 

 majority of the Protists that we still know, belong to that fourth 

 class which is incapable of development. The persistence of the 

 ephemeral creations of our second and third classes would natu- 

 rally be secured only so long as circumstances continued favour- 

 able to their renewed primordial generation, but from the teleo- 

 logical standpoint the first class must be described as that of the 

 completely abortive attempts at creation." 



These, and similar more or less interesting fancies to which we 

 attribute no great importance, are all derived from Haeckel's 

 hypothesis of Autogony (" Generelle Morphologic der Organis- 

 men," 179 seq.), which he set up after his beautiful discoveries on 

 the simplest organisms now existing — the Moncra and the Protists. 

 From this work we select the following passage : — " Doubtless we 

 must imagine the act of autogony, the first spontaneous origin of 

 the simplest organisms, to be quite similar to the act of crystal- 

 lization. In a fluid, holding in solution the chemical elements 

 composing the organism, in consequence of certain movements of 

 the various elements among themselves, certain points of attraction 

 are formed, at which the atoms of the organogenetic elements 

 (carbon, oxygen, hydrogen, nitrogen) enter into such close contact 

 with one another that they unite in the formation of a complex 

 ternary or quaternary molecule. This primary group of atoms — 

 perhaps a molecule of albumen — now acts like the analogous crystal- 



* It is a simpler and more probable explanation that these low organisms 

 continue to exist because there is room for them. They remain in spite of 

 differentiation and in consequence of differentiation. 



