288 THE INDUCTIONS OF BIOLOGY. 



nodes which the leaf-bearing axis commonly possesses, the 

 flowering axis differs by the absence of rudimentary lateral 

 axes. In a leaf-bearing shoot the axil of every leaf usually 

 contains a small bud, which may or may not develop into a 

 lateral shoot; but though the petals of a flower are homo- 

 logous with leaves, they do not bear homologous buds at 

 their bases. Ordinarily, too, the foliar appendages of sexual 

 axes are much smaller than those of sexless ones — the 

 stamens and pistils especially, which are the last formed, 

 being extremely dwarfed; and it may be that the absence of 

 chlorophyll from the parts of fructification is a fact of like 

 meaning. Moreover, the formation of the seed-vessel appears 

 to be a direct consequence of arrested nutrition. If a gloved- 

 finger be taken to represent a growing shoot, (the finger 

 standing for the pith of the shoot and the glove for the peri- 

 pheral layers of meristem and young tissue, in which the 

 process of growth takes place) ; and if it be supposed that 

 there is a diminished supply of material for growth; then, it 

 seems a fair inference that growth will first cease at the apex 

 of the axis, represented by the end of the glove-finger; and 

 supposing growth to continue in those parts of the peripheral 

 layers of young tissue that are nearer to the supply of nutri- 

 ment, their further longitudinal extension will lead to the 

 formation of a cavity at the extremity of the shoot, like that 

 which results in a glove-finger when the finger is partially 

 withdrawn and the glove sticks to its end. Whence it seems, 

 both that this introversion of the apical meristem may be 

 considered as due to failing nutrition, and that the ovules 

 growing from its introverted surface (which would have been 

 its outer surface but for the defective nutrition) are extremely 

 aborted homologues of external appendages : both they and 

 the pollen-grains being either morphologically or literally 

 quite terminal, and the last showing by their dehiscence the 

 exhaustion of the organizing power.* 



* In partial verification, Mr. Tansley writes : — " Prof. Klebs of Basel has 

 shown that in Hydrodictyon^ gametes can only be produced by the cells of 



