TUBERCULOSIS. 
213 
isease arises, therefore, either by direct inoculation, by con- 
igion, or, finally, by germs suspended in the air, or contained 
i the peculiar tuberculous matter. According to Professor 
/alley, hereditary tendency may be divided into direct and 
idirect: the former, when it is transmitted by a sire or dam 
> its immediate progeny ; the latter, when only transmitted 
> the second or third generation, constituting atavism. No 
redisposing cause with which we are acquainted exercises 
ich a potent influence in the production of tubercle as this; 
om sire to son, from dam to offspring, from generation to 
eneration, often in unbroken succession, the fatal tendency 
transmitted ; the more consanguinity is multiplied the more 
le tendency is increased, and the greater the virulence of the 
^suiting products. 
No animal whose system is tainted even in the slightest 
egree, or in whose history there exists the slightest suspicion 
f tubercle, should be used for breeding purposes. 
A remarkable case, proving the transmissibility of the 
isease from the male parent to the progeny, is published by 
ippelius: A stock-breeder purchased a bull, and with him 
?rved ten of his cows. The bull was found to be affected 
r ith tuberculosis, and for this reason was killed. All the 
alves of the ten cows which had been bred to this bull had 
ventually to be killed, because of this affection. The first 
ymptoms of the disease in the calves were manifested when 
ley had passed the adult age. 
Williams says it is not only hereditary, but congenital; and 
e has seen a calf three months old, which had thriven well 
ntil within two or three days of its death, filled with caseous, 
alcareous, and gray, tuberculous ulcers. In this calf the 
’hole of the serous membranes were affected, which must 
ave been formed in the uterus. 
Adams relates an instance, from among many others, in 
<’hich the lesions of the disease were observed in a calf which 
ied a few hours after its birth, the mother at the time being 
fleeted with the disease. Semmes relates five cases of phthisis 
- r hich he met with in the foetuses of cattle, and says these 
ases sufficiently prove that it can be developed during the 
mbryonic stage. 
