1 66 THE BEGINNINGS OF LIFE. 



may, under certain conditions, be partially or wholly 

 obliterated, and the ultimate structure assumed without 

 passing through them, so here it is to be inferred that 

 the process of cell formation may, in some cases, be 

 passed over. Thus the hypothesis of evolution prepares 

 us for these two radical modifications of the cell doc- 

 trine which the facts oblige us to make. It leads us to 

 expect, that as structureless portions of protoplasm 

 must have preceded cells in the process of general 

 evolution, so in the special evolution of each higher 

 organism there will be an habitual production of cells out 

 of structureless blastema. And it leads us to expect, that 

 though generally the physiological units composing a 

 structureless blastema will display their inherited pro- 

 clivities by cell development and metamorphosis ; there 

 will nevertheless occur cases in which the tissue to 

 be formed is formed by direct transformation of the 

 blastema V 



Fully admitting, therefore, that the c cell ' is a 

 most important structure, that it is a kind of whole 

 having in complex organisms a subordinate individu- 

 ality of its own, that cells do frequently multiply by 

 division of pre-existing cells, that they are in fact 

 morphological units, which by their uniformity of struc- 

 ture and wide-spread diffusion throughout the tissues 

 of both plants and animals may well claim to be the 

 morphological units still, we must not, on this ac- 

 count, endow them with an undue importance. We have 

 1 Loc. cit. vol. ii. p. 12. 



