-V 



404 



PROVISIONAL HYPOTHESIS OF PANGENESIS. Chap. XXVII. 



forms of metamorphosis and metagenesis, as well as the so- 



called growth of the higher animals, in which structure changes 

 though not in a striking manner, depends on the presence of 

 gemmules thrown off at each period of life, and on their develop- 

 ment, at a corresponding period, in union with preceding cells. 

 Such cells may be said to be fertilised by the gemmules which 

 come next in the order of development. Thus the ordinary act 

 of impregnation and the development of each being are closely 

 analogous processes. The child, strictly speaking, does not grow 

 into the man, but includes germs which slowly and successively 

 become developed and form the man. In the child, as well as 

 in the adult, each part generates the same part for the next 

 generation. Inheritance must be looked at as merely a form 

 of growth, like the self-division of a lowly-organised unicellular 

 plant. Eeversion depends on the transmission from the fore- 

 father to his descendants of dormant gemmules, which occa- 

 sionally become developed under certain known or unknown 

 conditions. Each animal and plant may be compared to a bed 

 of mould full of seeds, most of which soon germinate, some lie 

 for a period dormant, whilst others perish. When we hear it 

 said that a man carries in his constitution the seeds of an in- 

 herited disease, there is much literal truth in the expression. 



Finally, the power of propag 



possessed by each separate 



cell, using the term in its largest sense, determines the repro- 

 duction, the variability, the development and renovation of each 

 living organism. No other attempt, as far as I am aware, has 



confessedly is, to connect under 



We 



been made, imperfect 



one point of view these several grand classes of facts 

 cannot fathom the marvellous complexity of an organic being 

 but on the hypothesis here advanced this complexity is much 

 increased. Each living 



be looked 



ocosm 



little universe, formed of a host of self-propagating 



ganisms, inconceivably minute and as numerous as the 



heave 











n. 







