Mr. Spencer does not here say expressly that Erasmus Darwin and Lamarck considered inheritance of functionally produced modifications to be the sole explanation of the facts of organic life; modern writers on evolution for the most part avoid saying anything expressly; this nevertheless is the conclusion which the reader naturally draws—­and was doubtless intended to draw—­from Mr. Spencer’s words.  He gathers that these writers put forward an “utterly inadequate” theory, which cannot for a moment be entertained in the form in which they left it, but which, nevertheless, contains contributions to the formation of a just opinion which of late years have been too much neglected.

This inference would be, as Mr. Spencer ought to know, a mistaken one.  Erasmus Darwin, who was the first to depend mainly on functionally produced modifications, attributes, if not as much importance to variations induced either by what we must call chance, or by causes having no connection with use and disuse, as Mr. Spencer does, still so nearly as much that there is little to choose between them.  Mr. Spencer’s words show that he attributes, if not half, still not far off half the modification that has actually been produced, to use and disuse.  Erasmus Darwin does not say whether he considers use and disuse to have brought about more than half or less than half; he only says that animal and vegetable modification is “in part produced” by the exertions of the animals and vegetables themselves; the impression I have derived is, that just as Mr. Spencer considers rather less than half to be due to use and disuse, so Erasmus Darwin considers decidedly more than half—­so much more, in fact, than half as to make function unquestionably the factor most proper to be insisted on if only one can be given.  Further than this he did not go.  I will quote enough of Dr. Erasmus Darwin’s own words to put his position beyond doubt.  He writes:-

“Thirdly, when we enumerate the great changes produced in the species of animals before their nativity, as, for example, when the offspring reproduces the effects produced upon the parent by accident or culture, or the changes produced by the mixture of species, as in mules; or the changes produced probably by exuberance of nourishment supplied to the foetus, as in monstrous births with additional limbs; many of these enormities are propagated and continued as a variety at least, if not as a new species of animal.  I have seen a breed of cats with an additional claw on every foot; of poultry also with an additional claw and with wings to their feet; and of others without rumps.  Mr. Buffon” (who, by the way, surely, was no more “Mr. Buffon” than Lord Salisbury is “Mr. Salisbury”) “mentions a breed of dogs without tails which are common at Rome and Naples—­which he supposes to have been produced by a custom long established of cutting their tails close off.” {102a}