1 68 Animal Life and Intelligence. 



there is a gradual and, increasing accommodation of succes- 

 sive generations of organisms to changed conditions which 

 remain constant, then such transmission will be rendered 

 probable. I do not know that there are observations of 

 this kind of sufficient accuracy" to warrant our accepting 

 this conclusion as definitely proved. 



Attention may here be drawn to a peculiar and remark- 

 able mode of influence. If a pure-bred mare have foals by 

 an ill-bred sire, they will be ill-bred. This we can readily 

 understand. But if she subsequently have a foal by a 

 perfectly well-bred sire, that foal, too, may in some cases 

 be tainted by the blemish of the previous sire. So, too, 

 with dogs. If a pure-bred bitch once produce a mongrel 

 litter, no matter how carefully she be subsequently 

 matched, she will have a tendency to give birth to pups 

 with a mongrel taint. This subsequent influence of a 

 previous sire is a puzzling fact. It may be that some of 

 the male germ-nuclei are absorbed, and influence the germ- 

 cells of the ovary. But this seems an improbable solution 

 of the problem. It is more likely, perhaps, that in the 

 close relation of mother and foetus during gestation, each 

 influences the other (how it is difficult to say). On this 

 view the bitch retains the influence of the mongrel puppies 

 — is herself, in fact, partially mongrelized — and therefore 

 mongrelizes subsequent litters. It would not be safe, how- 

 ever, to base any far-reaching conclusions on so peculiar a 

 case, the explanation of which is so difficult. At all events, 

 it is impossible to exclude the possibility of direct action on 

 the germ, though the particular nature of the results of 

 such influence are noteworthy. 



We may pass now to the evidence that has been adduced 

 in favour of a cumulative effect in the exercise of function, 

 or of the inheritance of the results of use or disuse. Here, 

 again, it must be remembered that no one questions the 

 effects of use and disuse in the individual. What we seek 

 is convincing evidence that such effects are inherited. 



Physiologically, the effects of use or disuse are, in the 

 main, effects on the relative nutrition, and hence on the 



