ON THK (JENKTIC VIKW OF XA'ICRE. 297 



giowu life, the unification of thought on these niattere, is 

 quite as important in the history of science as tlie abolition 

 of the supposed fundamental difference between animal 

 and vegetable growth or between normal and abnormal (or 

 pathological) development. The reduction of all these 

 seemingly so different changes to the one great problem 

 of cellular structure, cellular growth, and cellular division 

 marks one of the greatest achievements of our century. 

 " Our position with regard to the cell is similar to that 

 of investigators towards the whole animal or vegetable 

 body a hundred years ago, before the discovery of the 

 cell theory."^ 



Anticipations of this generalisation, of the condensation 

 of the whole problem of animal and vegetable embryology, 

 of generation, growth, and organic development in the 

 formula, " omnis cellula ex cellula," have indeed existed 

 since the time of Harvey, who, in addition to the great 

 discovery of the circulation of the blood, laid down the 

 thesis, " omnp vivuni ex ovo." " Th(> further correct 



' See O. Hertwig, " Thy Cell, " important of the organs of the 



' Outlines of General Anatomy and i adult, nor by sudden nietamor- 



Physiology.' Transl. by Campbell, phosis of a formative substance 



1895, p. 11. I into a miniature of the \vhole, 



- One of the best expositions of ' which subsequently grows, but by 



Harvey's idea.s is to be found in epigenesis, or successive diffeientia- 



Huxley's article on " Evolution in tion of a relatively homogeneous 



Biologj'" in tlie ninth edition of rudiment into the parts and struc- 



the ' Encyclop;cdia Britannica.' He 

 there also refers to Aristotle's 

 opinions. " One of Harvey's prime 

 objects is to defend and establish, 



tures which are characteristic of 

 the adult." In the sequel of his 

 exposition, after maintaining epi- 

 genesis or after-formation against 



on the basis of direct observation, i evolution in the older sense or pre- 



the (jpinion already held by Aris- , formation, Huxley, however, makes 



totle, that in the higher animals [ a passing remark that " though the 



at any rate the formation of the doctrine of epigenesis, as uiulerstood 



new organism by the process of I by Harvey, has definitely triumphed 



generation takes place, not sud- over the doctrine of evolution, . . . 



denly by simultaneous accretion of it is not impossible that, when the 



rudiments of all, or of the must analysis of the jirocess of develop- 



