THE LAMARCKIAN PRINCIPLE 57 



slow. But when the wing had become so small, that exercise 

 was out of the question, then we should have expected all 

 trace of it to disappear rapidly. Now this is just what in this 

 and hundreds of like cases we do not find. When once the 

 organ has been reduced to the point of absolute uselessness, it 

 often lingers on with astonishing persistence, though there are, 

 it is true, many examples of complete disappearance. Of the 

 five digits of the normal hand the bird has only three remaining, 

 and of the two missing probably only one is represented by a 

 trace in the embryo. 



Such instances of complete loss do not in the least stand in the 

 way of my argument, which is this : If partial disuse can greatly 

 reduce an organ, complete disuse ought in every case to cause 

 its total and comparatively rapid disappearance. If it be urged 

 that all vestiges are gradually vanishing, the answer is that in 

 many cases organs reached the vestigial state ages ago and still 

 they linger on. For ages the horse's forefoot has borne only 

 one toe and yet there still remain the two so-called splint bones, 

 that once carried a toe on either side. 



I have tried to show that the Lamarckian explanation of 

 vestiges fails to explain the facts. There is what I consider 

 a satisfactory explanation which I hope soon to put before the 

 reader. I propose first to take some other problems which 

 Lamarckism fails to solve. 



Mr Herbert Spencer has written much on this subject. To The stag's 

 him the great antlers and the great development of muscle and ar 

 ligament for carrying them, present a phenomenon for which we 

 can account only if we consider the various associated develop- 

 ments to be the inherited results of exercise. We can imagine, 

 he says, that congenital variations might be accumulated, and the 

 antlers by themselves might be accounted for in this way. But 

 they would be an insupportable burden, did not other variations 

 arise simultaneously giving the body the strength to carry so 

 great a weight. Such co-adaptation and co-operation can be ex- 

 plained, he contends, only on Lamarckian principles. 



He has chosen this battlefield for himself, and considers that 

 here he has a very strong position. The problem which he has 



