274 Evolution and Adaptation 



organized nature arranged in a discontinuous series of groups 

 differing from each other by differences which are Specific ; 

 on the other hand, we see the diverse environments to which 

 these forms are subject passing insensibly into each other. 

 We must admit, then, that if the steps by which the diverse 

 forms of life have varied from each other have been insensi- 

 ble, — if, in fact, the forms ever made up a continuous series, 

 — these forms cannot have been broken into a discontinuous 

 series of groups by a continuous environment, whether acting 

 directly as Lamarck would have, or as selective agent as Dar- 

 win would have. This supposition has been generally made 

 and admitted, but in the absence of evidence as to Variation 

 it is nevertheless a gratuitous assumption, and, as a matter of 

 fact, when the evidence as to Variation is studied, it will be 

 found to be in a great measure unfounded." 



There is a fair number of cases on record in which discon- 

 tinuous variations have been seen to take place. Darwin him- 

 self has given a number of excellent examples, and Bateson, 

 in the volume referred to above, has brought together a large 

 and valuable collection of facts of this kind. 



Some of the most remarkable of these instances have been 

 already referred to and need only be mentioned here. The 

 black-shouldered peacock, the ancon ram, the turnspit dog, 

 the merino sheep, tailless and hornless animals, are all cases 

 in point. In several of these it has been discovered that the 

 young inherit the peculiarities of their parents if the new 

 variations are bred together; and what is more striking, if 

 the new variation is crossed with the parent form, the young 

 are like one or the other parent, and not intermediate in 

 character. This latter point raises a question of fundamental 

 importance in connection with the origin of species. 



Darwin states that he knows of no cases in which, when 

 different species or even strongly marked varieties are crossed, 

 the hybrids are like one form or the other. They show, he be- 

 lieves, always a blending of the peculiarities of the two parents. 



