156 HEREDITARY DISEASES OF HORSES AND CATTLE. 
hind feet, with the corresponding tarsal bones — a variety 
analogous to the one presented by six-toed or six-fingered 
families of the human race. 
Other cases could be adduced. We cannot, however, term 
such singular varieties as accidental, since there is nothing in 
the phenomena of nature to which the term accident can well 
be applied. The characters are doubtless the result of some 
organic change proper to the animals in which they appeared ; 
and their transmission to their progeny is only the exemplifi- 
cation of a lav * 7 common to other cases of transmitted characters. 
It is generally allowed that congenital varieties of this cha- 
racter tend to become hereditary, but that changes wrought 
in an animal after birth are not thus transmitted to offspring. 
This assertion is especially true in respect of deformities and 
mutilations, the result of accident or of man’s caprice. Changes 
of this kind occurring during the animal’s life commonly end 
with it, and have no obvious influence on its progeny. Had 
nature wrought otherwise, the mischances of all preceding 
ages would have been entailed on us ; and cropped dogs and 
dock-tailed horses would be born ready to our use. But 
although deformities of this kind are not hereditary, there are 
certain acquired conditions of the body, the consequence of 
disease, which are frequently conveyed from parent to off- 
spring. The state of health of either parent, particularly of 
the mother, at the time when the existence of the offspring 
commences, has a strong influence in the production of 
healthy or unhealthy progeny. We shall adduce a great 
many examples in support of this position in the course of 
the essay. 
The applicability of these remarks to the question of here- 
ditary disease is sufficiently obvious. If new characters are 
produced in domesticated animals, because they have been 
taken from their primitive conditions, and exposed to the 
operation of influences unnatural to them, we can have no 
reason to doubt that deviations of structure, “ whether in the 
way of deficiency or of excess, or any other new develop- 
ment, are occasionally produced and transmitted; and with 
these deviations, certain propensities to, or conditions of 
morbid action in the parts thus abnormally organized.” 
Generally the offspring is born free from disease,* conse- 
* Mr. G. Baker, V.S., Reigate, relates the case of a mare that was farcied , 
and, the owner breeding from her, the foal showed symptoms of farcy soon 
after birth, and died glandered. — ‘ Veterinarian vol. xiii. 
We have heard of a similar instance, where the farcied marc was bred 
from and the mare survived, but the foal exhibited symptoms of farcy and 
died. 
These cases arc congenilal, but diseases in which the foetus participates 
