GENESIS. 285 



Where multiplication is carried on by heterogenesis we 

 find, in numerous cases, that agamogenesis continues as long 

 as the forces which result in growth are greatly in excess of 

 the antagonist forces. Conversely, we find that the recur- 

 rence of gamogenesis takes place when the conditions are 

 no longer so favourable to growth. In like manner where 

 there is homogenetic multiplication, new individuals are usu- 

 ally not formed while the preceding individuals are still 

 rapidly growing — that is, while the forces producing growth 

 exceed the opposing forces to a great extent ; but the forma- 

 tion of new individuals begins when nutrition is nearly 

 equalled by expenditure. A few out of the many facts which 

 seem to warrant these inductions must suffice. 



The relation in plants between fructification and innu- 

 trition (or rather, between fructification and such diminished 

 nutrition as makes growth relatively slow) was long ago 

 asserted by a German biologist — Wolff, I am told. Since 

 meeting with this assertion I have examined into the facts 

 for myself. The result has been a conviction, strengthened by 

 every inquiry, that some such relation exists. Uniaxial 



plants begin to produce their lateral, flowering axes, only 

 after the main axis has developed the great mass of its 

 leaves, and is showing its diminished nutrition by smaller 

 leaves, or shorter internodes, or both. In multiaxial plants 

 two, three, or more generations of leaf -bearing axes, or sex- 

 less individuals, are produced before any seed-bearing indi- 

 viduals show themselves. When, after this first stage of rapid 

 growth and agamogenetic multiplication, some gamogenetic 

 individuals arise, they do so where the nutrition is least ; — not 

 on the main axis, or on secondary axes, or even on tertiary 

 axes, but on axes that are the most removed from the 

 channels which supply nutriment. Again, a flowering axis 

 is commonly less bulky than the others: either much 

 shorter or, if long, much thinner. And further, it is an 

 axis of which the terminal internodes are undeveloped: the 

 foliar organs, which instead of becoming leaves become 



