224 THE INDUCTIONS OF BIOLOGY. 



and tri-section were followed by like results. And so with 

 their segments, similarly produced, until as many as fifty 

 polypes had resulted from the original one. Bodies when cut 

 off regenerated heads; heads regenerated bodies; and when 

 a polype had been divided into as many pieces as was prac- 

 ticable, nearly every piece survived and became a complete 

 animal. What, now, is the implication? We cannot 



say that in each portion of a Begonia-leaf, and in every 

 fragment of a Hydra^s body, there exists a ready-formed 

 model of the entire organism. Even were there warrant for 

 the doctrine that the germ of every organism contains the 

 perfect organism in miniature, it still could not be contended 

 that each considerable part of the perfect organism resulting 

 from such a germ, contains another such miniature. Indeed 

 the one hypothesis negatives the other. The implication 

 seems, therefore, to be that the living particles composing one 

 of these fragments, have an innate tendency to arrange them- 

 selves into the shape of the organism to which they belong. 

 We must infer that the active units composing a plant or 

 animal of any species have an intrinsic aptitude to aggregate 

 into the form of that species. It seems difficult to conceive 

 that this can be so; but we see that it is so. Groups of 

 units taken from ah organism (providing they are of a certain 

 bulk and not much differentiated into special structures) have 

 this power of re-arranging themselves. Manifestly, 



too, if we are thus to interpret the reproduction of an organism 

 from one of its amorphous fragments, we must thus interpret 

 the reproduction of any minor portion of an organism by the 

 remainder. When in place of its lost claw a lobster puts 

 forth a cellular mass which, while increasing in bulk, assumes 

 the form and structure of the original claw, we cannot avoid 

 ascribing this result to a play of forces like that which moulds 

 the materials contained in a piece of Begonia-leaf into the 

 shape of a young Begonia. 



§ 66. As we shall have frequent occasion hereafter to refer 



