CRITICAL REMARKS ON THE THEORIES OF 

 EPIGENESIS AND EVOLUTION. 



MR. G. C. BOURNE'S thoughtful paper in the April 

 number of " Science Progress " showed, in a very 

 interesting manner, how in the most recent and popular 

 evolutionary views — notably in those of Professor Weis- 

 mann — we have an unintentional return to hypotheses of the 

 eighteenth century (of Haller and Bonnet), which long ago 

 were considered as definitely refuted and had been discarded 

 accordingly. He also urged that this return was so far in 

 conflict with the doctrine of epigenesis that the truth of the 

 latter ran a risk of being thereby obscured and lost sight of. 



Nevertheless there is evolution and evolution, andl 

 though the form of evolution he combats is open to his; 

 criticism, it does not follow that there is any conflict be- 

 tween epigenesis and evolution otherwise understood In- 

 deed the idea of evolution, as I understand it, far from 

 being antagonistic, is complementary, to that of epigenesis. 



For me the term "evolution" has a predominantly 

 dynamic implication, while, by the word "epigenesis," I 

 would mainly refer to the material results of evolution — 

 the facts concerning order, form and relation of a developing 

 organism's several parts. 



A process of epigenesis may be conceived of as taking 

 place in two different ways, either mainly through external 

 agencies or through an internal cause. Now for the de- 

 velopment of the ovum a fit environment is of course neces- 

 sary, as due physical external agencies are required for the 

 development of a grain of corn. Still it is the nature and 

 internal condition of the living corn-grain which is, par 

 excellence, the cause of its growth, and such is also the case 

 as regards the living ovum. The term "evolution" may 

 be employed, as it has been, to denote that the successive 

 formation of parts not previously existent is due, not to 

 their imposition from without, but to their generation from 

 within. Used in this sense " evolution " is not obnoxious to 



