492 
CALCULI IN THE LACTIFEROUS DUCTS. 
character. This incrustation is of uniform thickness, about the 
eighth of an inch, and envelops the internal substance, which is 
much less firm, being very friable, striated, white, and of a chalky 
nature. From its appearance I should suppose it to be composed 
chiefly of carbonate of lime. 
Remarks . — Upon my first visit to this cow, I was reminded by 
the proprietor that I attended her, a twelvemonth or so since, for a 
sore nipple and obstruction of milk: I recollected the circumstance, 
and, seeing the next day a person who had formerly been milker 
upon the farm, I made further inquiries concerning the animal, 
and vvas informed that at different periods she had experienced 
great difficulty in getting milk from this quarter of the mamma, 
her first attack being about four years since ; and that she had on 
several occasions, when the milk would not flow, forced through 
the natural orifice in the teat small stones. The cow would then 
milk well enough, and continue to do so for months, or until others 
found their way into the duct, which she then forced down and 
extracted in a similar manner; they were, of course, much smaller 
than the one I had to deal with. I have now little doubt that the 
excoriation at the end of the teat just referred to was produced by 
the exit of one of these bodies. 
Upon my assigning as a probable cause for their presence the 
want of care in milking dry, the owner informed me that he had 
great confidence in the former as well as the present milker; and 
that, from the time the cow first yielded milk to the present period, 
he did not believe there had been any negligence in this respect ; 
and consequently the idea of such a circumstance being in any 
way connected with the formation of these morbid concretions 
must have little weight. 
We must therefore, I imagine, come to the conclusion that their 
production depends more upon a constitutional than a local cause. 
Whether they are eliminated direct from the blood by any altered 
chemical agency, or depend upon the presence of the earthy salts, 
of which they are composed, existing in excess in the secretion 
itself, and deposited from the milk — or owe their existence to some 
structural or functional alteration in the gland — or whether they 
arise from defective digestion and assimilation, or from a com- 
bination of these causes, — are questions for the veterinary patho- 
logist to direct his attention to. And when a more extended 
knowledge of animal chemistry than at present, I fear, exists among 
us shall be diffused, we may hope to have important results from 
the light which it cannot fail to throw on the investigation into 
the causes of the production of calculous concretions in the animal 
body. 
Perhaps no division of our science has received less attention 
