34 CREATIVE INVOLUTION 



ferent aspects of the same great law. Considered in the 

 light of this law, the evolution of organic life breaks up 

 into a series of periods, each advancing according to a 

 fixed formula, and this periodical progression seems to 

 me to claim a place among the vast cosmic rhythms 

 which have in all ages fascinated the minds of philoso- 

 phers. . . . 



" Having thus come upon traces of three consecutive 

 units of structure, the chromidial unit, the cell and the 

 polyp or, as it will be called later on, the gastraeal unit, 

 each in turn yielding new organisms of a type higher 

 than its own, the idea naturally occurred to me that other 

 higher units might be discovered by the help of which 

 we might be able to analyse the higher and more com- 

 plicated organisms more satisfactorily than by the cell. 

 It appeared, indeed, as if morphology might have been 

 befogged by the universal custom of analysing all or- 

 ganisms by the cell alone, and that the progress of the 

 science of life might have been retarded in consequence 

 of our restricting ourselves almost entirely to accumu- 

 lating facts and working with a conception of the cell 

 which requires emendation. Reviewing animal forms 

 with the obj ect of finding traces of such units, I was able 

 to reconstruct synthetically two more, the annelidan and 

 the vertebrate, and thus to form a series of five distinct 

 units of structure. . . . 



" Organic life is thus seen advancing out of the dim 

 past upon a series of waves, each of which can be scanned 

 in detail until we come to that one on which we ourselves, 

 the organisms of to-day, and the human societies to 

 which we belong are swept onward. Here we must nec- 

 essarily pause, but can we doubt that the great organic 

 rhythm which has brought life so far, will carry it on to 

 still greater heights in the unknown future? . . . 



