THE WONDERS OF LIFE 



even long after its formation was incapable of support- 

 ing organic life on its surface. This only became pos- 

 sible when the surface of the glowing planet had suffi- 

 ciently cooled for liquid water to settle on it. Until 

 this stage carbon could not enter into those combina- 

 tions with other elements (oxygen, hydrogen, nitrogen, 

 and sulphur) which led to the formation of plasm. As 

 I intend to deal with this process of archigoiiy, or spon- 

 taneous generation, in a special chapter, I leave it for the 

 present, and confine myself to the study of tocogony, or 

 parental generation. 



The various forms of tocogony, or the reproduction of 

 living things, are generally divided into two large groups ; 

 on the one hand there is the simple form of asexual gen- 

 eration (monogony), and on the other the complex form 

 of sexual generation (amphigony). In asexual genera- 

 tion the action of one individual only is needed, this 

 providing a product of transgressive (redundant) growth 

 which develops into a new organism. In sexual genera- 

 tion it is necessary for two different individuals to unite 

 in order to produce a new being from themselves. This 

 amphigony (or generatio digenea) is the sole form of re- 

 production in man and most of the higher animals. But 

 in many of the lower animals and most of the plants we 

 find also asexual multiplication, or monogony, by cleav- 

 age or budding. In the lowest organisms, the monera 

 and many of the protists, fungi, etc., the latter is the 

 only form of propagation. 



Strictly speaking, monogony is a universal life-proc- 

 ess; even the ordinary cell-cleavage, on which depends 

 the growth of the histona, is a cellular monogony. 

 Hence historical biology must say that monogony is the 

 older and more primitive form of parental generation, 

 and that amphigony was secondarily developed from 

 it. It is important to emphasize this because, not only 



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