46 METAMOEPHOSES OF MAN 



CHAPTER VI. 



GENEEAL PEOCESSES OF TEANSFOEMATION CONCLUSION. 



Having sketched the more comprehensive features of 

 embryonic development in general, and of that of 

 mammals in particular, we shall now examine the various 

 methods by which these phenomena are brought 

 about. We saw, at the outset, that Nature does her 

 work in a far more complete manner than some 

 philosophers imagine, and that she accomplishes her 

 purpose by a series of different processes, rather than 

 'by a single one. 



Of these processes we may mention two by name — 

 JEpigenesis and Evolution ; terms which have been for 

 ages the standards of rival schools, and the subjects 

 of many a noisy controversy. 



According to the doctrine of Epigenesis, neither 

 tissues nor organs exist in the embryo prior to their 

 appearance ; they are all formed upon the spot, suc- 

 cessively, and, as it were, spontaneously also. The 

 innate nature of each animal determines their form 

 and structure. The Evolution theory, on the other 

 hand, asserts that all the organs of the future being 

 exist in the germ ; that the latter has the power of 

 growth alone, and is unable to give the being a hair, 

 a feather, or a scale, in addition to what it already 

 possesses, if it be an animal; or a leaflet, if it be a 

 plant. 



