218 



THE INDUCTIONS OF BIOLOGY. 



separated from the parent-plant under the shape of a centre ; 

 and the embryo-cell, though not absolutely separated from 

 the parent, is still no longer subordinate to the organizing 

 forces of the parent. So that when, the embryo-cell having 

 been fertilized by matter from the pollen-tube, the develop 

 ment commences, it proceeds without parental control : 

 the new individual, though remaining physically united 

 with the old individual, becomes structurally and functionally 

 separate while still only a centre of development ; and takes 

 on its axial form by processes of its own the old individual 

 doing no more than supply materials. Through 



out the animal kingdom, the new individuals produced by 

 gamogenesis, are obviously separated in the shape of centres 

 of development wherever the reproduction is oviparous . the 

 only conspicuous variation being in the quantity of nutritive 

 matter bequeathed by the parent to the new centre of de 

 velopment, at the time of its separation. And though, where 

 the reproduction is viviparous, the process appears to be 

 different, and in one sense is so ; yet, intrinsically, it is the 

 same. For in these cases, the new individual really detaches 

 itself from the parent while still only a centre of develop 

 ment ; but instead of being finally cast off in this state, it is 

 re-attached, and supplied with nutriment until it assumes a 

 more or less complete axial structure. 



77. Under all its various forms, the essential act in gamo 

 genesis, is the union of two centres or cells, produced by 

 different parent organisms : the sperm-cell being the male 

 product, and the germ -cell the female. There are very 

 many modes and modifications of modes in which these 

 cells are produced ; very many modes and modifications of 

 modes by which they are brought into contact ; and very 

 many modes and modifications of modes by which the result 

 ing fertilized germs have secured to them the fit conditions 

 for their development. But passing over these many diver 

 gent arid re-divergent kinds of sexual multiplication, which 



