INHERITANCE OF FUNCTIONALLY-WROUGHT CHANGES. 693 



alone prove tlie Neo-Darwinian doctrines untenable ; and the fact 

 that we have three unsolved problems seems to me fatal. 



From this negative evidence, turn now to the positive evi- 

 dence. This falls into several groups. 



There are first the facts collected by Mr. Darwin, implying 

 functionally-altered structures in domestic animals. The hypo- 

 thesis of panmixia is, as we have seen, out of court ; and there- 

 fore Mr. Darwin's groups of evidences are reinstated. There is 

 the changed ratio of wing- bones and leg-bones in the duck ; there 

 are the drooping ears of cats in China, of horses in Russia, of 

 sheep in Italy, of guinea-pigs in Germany, of goats and cattle in 

 India, of rabbits, pigs, and dogs in all long-civilized countries. 

 Though artificial selection has come into play where drooping 

 has become a curious trait (as in rabbits), and has probably 

 caused the greater size of ears which has in some cases gone along 

 with diminished muscular power over them ; yet it could not 

 have been the initiator, and has not been operative on animals 

 bred for profit. Again there are the changes produced by climate ; 

 as instance, among plants, the several varieties of maize estab- 

 lished in Germany and transformed in the course of a few gene- 

 rations. 



Facts of another class are yielded by the blind inhabitants of 

 caverns. One who studies the memoir by Mr. Packard on The 

 Cave Fauna of North America^ <tc., will be astonished at the 

 variety of types in which degeneration or loss of the eyes has 

 become a concomitant of life passed in darkness. A great 

 increase in the force of this evidence will be recognized on learn- 

 ing that absence or extreme imperfection of visual organs is 

 found also in creatures living in perpetual night at the bottoms of 

 deep oceans. Endeavours to account for these facts otherwise 

 than by the effects of disuse we have seen to be futile. 



Kindred evidence is yielded by decrease of the jaws in those 

 races which have had diminished use of them — mankind and 

 certain domestic animals. Relative smallness in the jaws of 

 civilized men, manifest enough on comparison, has been proved 

 by direct measurement. In pet dogs — pugs, household spaniels 

 — we find associated the same cause with the same effect. Though 

 there has been artificial selection, yet this did not operate until 

 the diminution had become manifest. Moreover there has been 

 diminution of the other structures concerned in biting : there are 

 smaller muscles, feeble zygomata, and diminished areas for inser- 

 tion of muscles — traits which cannot have resulted from selec- 

 tion, since they are invisible in the living animal. 



In abnormal vision produced by abnormal use of the eyes we 

 have evidence of another kind. That the Germans, among 



