EEL ATION SHIP OF SPECIES. 257 



higher animals (natural species). Most valuable animals for a 

 test of non-segregating characters (and other matters besides) 

 would probably be the hybrid Bears mentioned before in this 

 article (hybrid Brown Polar, London Zoological Society). 



It can hardly be denied that the presence of intermediate 

 characters in divergent crosses (extreme species) suggests inter- 

 mediate, and therefore merging, evolution, such as I have found 

 evidence of in the results of hybridization which I have given 

 on p. 28. 



We are obliged to admit two cardinal points : — 



(1) Mendelians offer no explanation as to these intermediate 

 characters. 



Thus : " In the phenomena of hybridization between the 

 races of mankind the facts (fairly well-authenticated) must be 

 taken as pointing at all events to the existence of special 

 features in them." * 



And, again, as regards dimorphisms in Lepidoptera (p. 257) : 

 " The only other suggestion " [to the presence of factors] " which 

 can be made is that these distinctions are ultimately referable 

 to the effects of external conditions." 



And, again (p. 285) : " Of the consequences of specific crosses 

 in the stricter sense little is known, and no case has been fully 

 explored. But before any decision at all is pronounced or even 

 contemplated, the laws which govern the incidents of sterility 

 must be most carefully determined." 



On the other hand, we have the definite opinion on p. 289 : 

 "The conception of Evolution as proceeding through the gradual 

 transformation of masses of individuals by the accumulation of 

 inpalpable changes is one that the study of genetics shows 

 immediately to be false. Once for all, that burden so gratuitously 

 undertaken in ignorance of genetic physiology by the evolutionist 

 of the last century may be cast into oblivion." 



This brings us up against our second cardinal point : — 



(2) That we have the evidence of the development of many 

 extreme types of the same domestic (and even wild) animal 

 brought about by gradual divergence quite unconformable with 

 any system of factors, as now propounded. 



If I may make the suggestion, it appears to me that we must, 



* ' Mendel's Principles of Heredity,' p. 257. 

 Zool. 4th ser. vol. XVIII., July, 1914. s 



