470 INHEKITANCE. Chap. XII. 



born with exactly the same spot marked or scarred. Many 

 instances have been recorded of cats, dogs, and horses, which 

 have had their tails, legs, &c., amputated or injured, produc- 

 ing offsping with the same parts ill-formed ; but as it is not 

 very rare for similar malformations to appear spontaneously, 

 all such cases, may be due to coincidence. It is, however, an 

 argument on the other side that " under the old excise laws 

 " the shepherd-dog was only exempt from tax when without 

 " a tail, and for this reason it was always removed ; " 60 and 

 there still exist breeds of the shepherd-dog which are always 

 born destitute of a tail. Finally, it must be admitted, more 

 especially since the publication of Brown-Sequard's observa- 

 tions, that the effects of injuries, especially when followed by 

 disease, or perhaps exclusively when thus followed, are 

 occasionally inherited. 61 



Causes of Non-inheritance. 



A large number of cases of non-inheritance are intelligible 

 on the principle, that a strong tendency to inheritance does 

 exist, but that it is overborne by ho -tile or unfavourable 

 conditions of life. No one would expect that our improved 

 pigs, if forced during several generations to travel about and 

 root in the ground for their own subsistence, would transmit, 

 as truly as they now do their short muzzles and legs, and 

 their tendency to fatten. Dray-horses assuredly would not 

 long transmit their great size and massive limbs, if compelled 

 to live on a cold, damp mountainous region ; we have indeed 

 evidence of such deterioration in the horses which have run 

 wild on the Falkland Islands. European dogs in India often 

 fail to transmit their true character. Our sheep in tropical 

 countries lose their wool in a few generations. There seems 

 also to be a close relation between certain peculiar pastures 

 and the inheritance of an enlarged tail in fat-tailed sheep, 



60 ' The Bog,' by Stonehenge, 1867, reduced on the sirae part of the.se 

 p. 118. feathers, it seem; extremely prol able, 



61 The Mot-mot habitually bites as Mr. Salvin re narks (' Proc. Z< olog. 

 the bai*bs oft" the middle part of the Soc' 1873. p. 4 -'9), that this is due to 

 two central tail-feathers, and as the the inherited effects of long-continued 

 barbs are congenitally somewhat mutilation. 



