WEST OF SCOTLAND VETERINARY MEDICAL ASSOCIATION. 681 
met with a single case of true tubercular disease in a foetus. I 
know that some specific diseases are congenitally transmitted, but 
I question whether this particular one is. It has been argued, 
that the fact of young animals becoming the subject of tubercle is 
a proof of congenital transmission ; but the value of this idea is 
somewhat detracted from by the rapid manner in which tubercle 
is propagated by inoculation. On the other hand, it may be that 
the blood of the young animal may be imbued with some peculiar 
tubercular principle, which only waits favorable circumstances for 
it to become developed, and we have not to look far for instances 
in which morbid virus retains its vitality for many weeks out of 
the body even, as witness the length of time the virus of small¬ 
pox is preserved in glass tubes, and the length of time inter¬ 
vening between the receipt of a bite from a rabid dog, and the 
period at which symptoms are shown; as also with amoeba and 
rotifers, which retain vitality even when nearly dessicated, and 
await only lodgment in a suitable pabulum to start into newness 
of life. 
The fact of a mother being in a weakly state during pregnancy 
does not hypothetically explain satisfactorily the production of 
congenital tubercle, as we frequently find mothers whose blood is 
deteriorated, not only from a bad quality of food, but also from 
the presence in their system of actual organic disease, give birth 
to strong healthy progeny so long as there is no specific disease of 
the blood. And this strengthens my opinion that tubercle is a 
specific disease, and that other causes are in operation to produce 
it besides debility or inflammation. 
“Tubercle,” says Yirchow, “is a disease of extra-uterine life ; 
hereditary, but not congenital: hereditary, not as a disease, but 
as a disposition.” 
Intimately mixed up with this section of my subject is the 
hereditary or non-hereditary nature of tubercle. If it is proved 
it is congenital, the question is at once set at rest ; but is the 
disease hereditary, i. e. is it in existence at the time of the 
animal's birth, or rather, I should say, are the elements of the 
disease present in the system of the young, or is there only a 
liability to this particular form of disease from peculiarity of 
structure or conformation of texture? Ophthalmia is said to be 
hereditary; granted that it is, in so far as similarity of structure 
is concerned, thus rendering the eye more susceptible to inflam¬ 
matory action; so with navicularthritis, &c. There is only a 
tendency from consanguinity probably intensified by the system 
of in-and-in breeding, and from imperfect organisation. That this 
tendency may actually become developed into a positive dyscrasia, 
under favorable circumstances, I do not deny, and have even 
endeavoured to show that such is the case. No doubt, as savs 
