BLASTOGENIC VARIATIONS. 171 



lary ridges on the bulbs of the fingers, are the most per- 

 sistent of all the external characters that have yet been 

 examined. They are found to fall in three definite and 

 widely different classes. Each of these is a true race 

 in the sense in which that word was defined, transitional 

 forms being rare and the typical forms being frequent. 

 Galton thinks that the continual appearance of these 

 well-marked and very distinct patterns proves the 

 reality of the alleged positions of organic stability. 



A clear distinction between sports and varieties seems 

 to show itself also amongst the Lepidoptera. Thus 

 Standfuss * found that when a sport is crossed with its 

 parent form, the issue is sharply divided in both sexes 

 into specimens resembling either the sport or the nor- 

 mal form. There are no true intermediate forms, 

 though occasionally forms are observed in which the 

 characters are unsymmetrically mixed. When the nor- 

 mal form of a species is crossed with a gradually formed 

 local race, however, a series of intermediate forms is 

 obtained. We have seen also that De Vries, in his ex- 

 periments on plants, claims to have found a wide dif- 

 ference between mere varieties, and true sports such as 

 were obtained from (EnotJiera Lamarckiana. 



As already mentioned, sports have been stated to be 

 much more persistent in propagating their aberrant 

 characters than normal varieties, but the evidence in 

 favour of such a generalised statement is quite in- 

 sufficient. There are certainly a few instances which 

 strongly support it, but there are a good many more 

 which entirely fail to do so. Of the former, the in- 



*"Handbuch der palaartischen Gross-Schmetterlinge," Jena, 

 1896. 



