we must either assign to use and disuse such a predominant share in modification as to make it the feature most proper to be insisted on, or deny that the modifications, whether of mind or body, acquired during a single lifetime, are ever transmitted at all.  If they can be inherited at all, they can be accumulated.  If they can be accumulated at all, they can be so, for anything that appears to the contrary, to the extent of the specific and generic differences with which we are surrounded.  The only thing to do is to pluck them out root and branch:  they are as a cancer which, if the smallest fibre be left unexcised, will grow again, and kill any system on to which it is allowed to fasten.  Mr. Wallace, therefore, may well be excused if he casts longing eyes towards Weismannism.

And what was Mr. Darwin’s system?  Who can make head or tail of the inextricable muddle in which he left it?  The Origin of Species in its latest shape is the reduction of hedging to an absurdity.  How did Mr. Darwin himself leave it in the last chapter of the last edition of the Origin of Species?  He wrote:—­

“I have now recapitulated the facts and considerations which have thoroughly convinced me that species have been modified during a long course of descent.  This has been effected chiefly through the natural selection of numerous, successive, slight, favourable variations; aided in an important manner by the inherited effects of the use and disuse of parts, and in an unimportant manner—­that is, in relation to adaptive structures whether past or present—­by the direct action of external conditions, and by variations which seem to us in our ignorance to arise spontaneously.  It appears that I formerly underrated the frequency and value of these latter forms of variation, as leading to permanent modifications of structure independently of natural selection.”

The “numerous, successive, slight, favourable variations” above referred to are intended to be fortuitous, accidental, spontaneous.  It is the essence of Mr. Darwin’s theory that this should be so.  Mr. Darwin’s solemn statement, therefore, of his theory, after he had done his best or his worst with it, is, when stripped of surplusage, as follows:—­

“The modification of species has been mainly effected by accumulation of spontaneous variations; it has been aided in an important manner by accumulation of variations due to use and disuse, and in an unimportant manner by spontaneous variations; I do not even now think that spontaneous variations have been very important, but I used once to think them less important than I do now.”