sect, xiii.] INTRODUCTION. G9 



definite form of the type to a form of variety which has also in 

 some measure the character of definiteness. Is it not then possible 

 that the Discontinuity of Species may be a consequence and ex- 

 pression of the Discontinuity of Variation \ To declare at the 

 present time that this is so would be wholly premature, but the 

 suggestion that it is so is strong, and as a possible light on the 

 whole subject should certainly be considered. 



In view of such a possible solution of one of the chief parts 

 of the problem of Species it will be well to point out a line of 

 inquiry which must in that event be pursued. If it can be shewn 

 that the Discontinuity of Species depends on the Discontinuity of 

 Variation, we shall then have to consider the causes of the Dis- 

 continuity of Variation. 



Upon the received hypothesis it is supposed that Variation is 

 continuous and that the Discontinuity of Species results from the 

 operation of Selection. For reasons given above (pp. 15 and 1G) there 

 is an almost fatal objection in the way of this belief, and it cannot 

 be supposed both that all Variation is continuous and also that the 

 Discontinuity of Species is the result of Selection. With evidence 

 of the Discontinuity of Variation this difficulty would be removed. 



It will be noted also that it is manifestly impossible to suppose 

 that the perfection of a variety, discontinuously and suddenly 

 occurring, is the result of Selection. No doubt it is conceivable 

 that a race of Tulips having their floral parts in multiples of four 

 might be raised by Selection from a specimen having this character, 

 but it is not possible that the perfection of the nascent variety 

 can have been gradually built up by Selection, for it is, in its very 

 beginning, perfect and symmetrical. And if it may be seen thus 

 clearly that the perfection and Symmetry of a variety is not the 

 work of Selection, this fact raises a serious doubt that perhaps 

 the similar perfection and Symmetry of the type did not owe its 

 origin to Selection either. This consideration of course touches 

 only the part that Selection may have played in the first building 

 up of the type and does not affect the view that the perpetuation 

 of the type once constituted, may have been achieved by Selection. 



But if the perfection and definiteness of the type is not due 

 to Selection but to the physical limitations under which Variation 

 proceeds, we shall hope hereafter to gain some insight into the 

 nature of these limitations, though in the present state of zoological 

 study the prospect of such progress is small. In the observations 

 which follow I am conscious that the bounds of profitable specu- 

 lation are perhaps exceeded, and I am aware that to many this 

 may seem matter for blame; but there is, in my judgment, a 

 plausibility in the views put forward, sufficient at least to entitle 

 them to examination. They are put forward in no sense as a 

 formulated theory, but simply as a suggestion {'or work. It is, 

 besides, only in foreseeing some of the extraordinary possibilities 



