182 GEORGE JOHN ROMANES issi- 



possibly be themselves my l physiological sports,' 

 although they may very well be the consequences of 

 such a sport leading to physiological isolation, and so 

 to independent variation in two or three directions 

 simultaneously, till afterwards blended by inter- 

 crossing. And my reason for thinking this is that 

 ' Weismann's variations ' always arose in crops at 

 enormously long intervals of time. On the mere 

 doctrine of chances it therefore becomes impossible 

 to suppose that each of these variations was due to 

 a separate physiological sport, although it is easy to 

 see how each crop of them might have been so. For, 

 if not, why should they always have arisen in crops, 

 each member of which was demonstrably fertile with 

 the other members of that crop, while no less 

 demonstrably sterile with the original parent form ? 

 Therefore, what I see in these facts is precisely what, 

 upon my theory, I should expect to see, viz. first, a 

 ' primary variation,' or ' physiological sport,' arising 

 at long intervals ; secondly, closely following upon 

 this, a crop of ( secondary variations ' in the way of 

 slight morphological changes affecting two or three 

 different i strains ' simultaneously ; and thirdly, an 

 eventual blending of these strains by intercrossing 

 with one another without being able to intercross 

 with the surrounding and (at first) very much more 

 numerous parent form. 



But I can now quite understand why you thought 

 these facts were * dead against ' me ; you thought 

 that every single slight change of morphology must 

 (on my theory) have had a separate ' physiological 

 sport ' to account for it. This, however, most em- 



