CONGRUITY OF THE EVIDENCE 291 



forms of Phytozoa, which were actually seen by him to be derived 

 from one another by direct processes of transformation. In 

 summing up the results of his investigations he said ' : " Thus we 

 see that a single species, owing to its numerous modes of propaga- 

 tion, can pass through a number of very various forms of develop- 

 ment, which have been either erroneously arranged as distinct 

 genera, or at least as remaining stationary in those genera, although, 

 in fact, only transitionary stages." And, after a brief enumeration of 

 the principal changes he has witnessed among the derivatives of 

 this simple Alga, he adds the following important statement : " A 

 critical and comparative consideration of the foregoing facts would 

 therefore appear to render untenable almost all the principles 

 which modern systematists have hitherto adopted as the basis for 

 the construction of their Natural Kingdoms, Families, Genera, and 

 Species." 



It seems clear, in fact, that so long as organisms multiply by 

 mere ' discontinuous growth ' (fission or gemmation) there is 

 absolutely no reason to appeal to heredity except in the form of 

 ' organic polarity.' This would be all-sufficient for the preservation 

 of their hkeness under similar conditions ; for accounting for their 

 changes under dissimilar conditions ; and for their reversion (as 

 with crystals and double salts) ^ to old forms on renewal of old 

 conditions — a class of facts among organisms with which the 

 researches of many bacteriologists have made us perfectly familiar. 



It is, then, not till we get out of the great Ephemeromorphic 

 plexus, and come to organic forms which habitually multiply by 

 sperm-cells and germ-cells (or occasionally by the latter alone) 

 that heredity, as postulated by Darwin and Weismann, comes into 

 play : and it is, consequently, not till we reach such forms that it 

 would be possible for Natural Selection to be influential as a cause 

 of evolution. I make bold to say this notwithstanding the opposite 

 views held by Darwin himself, Weismann and others who, as is 

 well known, maintain that the influence of Natural Selection as a 

 producer of fitness between organisms and their circumstances is 

 one which is applicable to all forms of life. I maintain, however, 

 that for the chance-products originating by heterogenesis appeal 

 must be made to ' organic polarity ' alone. 



The evidence for the conjoint association of Organic Polarity 

 and Heterogenesis is far more certain, and indeed belongs to 



" Loc. cit, p. 559, ' See pp. 44-46. 



