OBJECTIONS TO THE THEORY OF NATURAL SELECTION 173 



always comes that many parts of the organization should have 

 been modified at the same time through variation and natural se- 

 lection? But there is no necessity for supposing that all the parts 

 of any being have been simultaneously modified. The most strik- 

 ing modifications, excellently adapted for some purpose, might, as 

 was formerly remarked, be acquired by successive variations, if 

 slight, first in one part and then in another; and as they would be 

 transmitted all together, they would appear to us as if they had 

 been simultaneously developed. The best answer, however, to the 

 above objection is afforded by those domestic races which have 

 been modified, chiefly through man's power of selection, for some 

 special purpose. Look at the race and dray horse, or at the grey- 

 hound and mastiff. Their whole frames, and even their mental 

 characteristics, have been modified; but if we could trace each 

 step in the history of their transformation — and the latter steps 

 can be traced — we should not see great and simultaneous changes, 

 but first one part and then another slightly modified and improved. 

 Even when selection has been applied by man to some one char- 

 acter alone — of which our cultivated plants offer the best instances 

 — it will invariably be found that although this one part, whether 

 it be the flower, fruit, or leaves, has been greatly changed, almost 

 all the other parts have been slightly modified. This may be at- 

 tributed partly to the principle of correlated growth, and partly 

 to so-called spontaneous variation. 



A much more serious objection has been urged by Bronn, and 

 recently by Broca, namely, that many characters appear to be of 

 no service whatever to their possessors, and therefore cannot have 

 been influenced through natural selection. Bronn adduces the 

 length of the ears and tails in the different species of hares and 

 mice — the complex folds of enamel in the teeth of many animals, 

 and a multitude of analogous cases. With respect to plants, this 

 subject has been discussed by Nageli in an admirable essay. He 

 admits that natural selection has effected much, but he insists that 

 the families of plants differ chiefly from each other in morpho- 

 logical characters, which appear to be quite unimportant for the 

 welfare of the species. He consequently believes in an innate tend- 

 ency toward progressive and more perfect development. He speci- 

 fies the arrangement of the cells in the tissues, and of the leaves 

 on the axis, as cases in which natural selection could not have 

 acted. To these may be added the numerical divisions in the parts 

 of the flower, the position of the ovules, the shape of the seed, when 

 not of any use for dissemination, etc. 



There is much force in the above objection. Nevertheless, we 



