280 HEREDITARY DISEASES OF HORSES AND CATTLE. 
tuberculous predisposition may not be frequently induced in 
embryo , from the neglect of the necessary conditions required 
for the healthy support of the cow. Sir James Clark has 
directed the attention of the public to this circumstance. 
He says, that a state of impaired health of the mother, 
whether constitutional or acquired, and particularly if caused 
by imperfect digestion and assimilation, is as productive of 
a tendency to scrofula and consumption in the children as if 
it had descended by hereditary transmission. 5 ’ 
(b.) The tubercular disease in horses is not near so common 
as in cattle. In young horses it is sometimes induced by im- 
perfect and insufficient food, rapid growth, and exposure to 
the vicissitudes of the weather. The mesenteric glands and 
mucous follicles of the small intestines are most generally 
affected in these cases — becoming enlarged and filled with 
purulent and tubercular matters, — but in old horses the lungs 
are the parts chiefly attacked, the symptoms assuming a 
glanderous character, such as nasal discharge, short cough, 
defective appetite, and general loss of condition. 
The next example is a disease of a scrofulous character, 
and, like unto the previous one, is evidently produced from 
a vitiated state of the blood. 
(e.) Scirrhous Tumours in Cattle . — These tumours are gene- 
rally seen in working oxen and bulls, old or full grown. 
They make their appearance without any apparent pain or 
constitutional disturbance; at first confined to the thyroid 
glands, and finally attack the submaxillary and parotid. The 
disease is known to the farmers in the west of England 
under the name of choke-ill , as, in the latter stages of the 
complaint, there is great difficulty of swallowing experienced, 
arising from the roots of the tongue and the throat becoming 
affected. When these symptoms appear, the animal quickly 
dies. 
A section of one of these tumours displays several 
abscesses, containing purulent and sometimes fetid matter, 
enclosed in fibro-cartilaginous cysts, and which never dis- 
charge themselves like unto healthy phlegmonous abscesses. 
Our case-book furnishes us with the history of many in- 
stances of the disease, proving unquestionably its hereditary 
character. 
The last two examples of hereditary disease are of a scrofu- 
lous character, and are recognized as constitutional disorders, 
continued from one generation to another, through the 
medium of the blood. However difficult it may be to 
imagine or conceive a fluid like the blood, ever in motion and 
change, being capable of hereditary taint, yet is it not really 
