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by making predisposition the ultimate fact, the starting- 
point. 
It is difficult to believe that the predisposition is equal 
in all cases. And indeed we need not dwell upon this 
point, for Dr. Weismann himself admits that the pre 
disposition may vary :— 
“ I freely admit that the predisposition to an Exercierknochen 
varies, and that a strongly-marked predisposition may be transmitted 
from father to son in the form of bony tissue with a more susceptible 
constitution.”—(Essays upon Heredity, vol. i., ist ed., p. 170.) 
The assertion that the predisposition can only be 
developed by exercise is true in some cases, but surely not 
in all. The instantaneous response of the water-ouzel to 
the stimulus presented by the touch of water, and the 
perfect dive which instantly follows, is surely an illustra 
tion of the predisposition which passes at one leap to 
perfect action. 
The assertion that no effect of exercise can be inherited 
seems to be contradicted by experience. The greyhounds, 
which could easily breathe the rarer air, although their 
parents could not, are a case in point, and something more. 
We may learn the same lesson from the case quoted by 
Mr. Darwin :— 
“ Every one knows that hard work thickens the epidermis on the 
hands ; and when we hear that with infants, long before their birth, 
the epidermis is thicker on the palms and soles of the feet than on 
any other part of the body, as was observed with admiration by 
Albinus, we are naturally inclined to attribute this to the inherited 
effects of long-continued use or pressure.”—(The Variation, vol. zz'., 
p. 297.) 
But if this is so, it is a bold assertion to declare that it 
does not matter to the next generation whether the pre 
disposition has been developed or not in ancestors.