Abortion in Cows. 
465 
5. That affected animals, whilst grazing, would sometimes 
impart the malady to in-calvers in adjacent fields. 
tj. That a change of hay or grass (all other circumstances re- 
maining unchanged) would be ineffectual to arrest the malady. 
7. That animals known to have recently aborted would be 
capable of conveying the infection to others. 
Animals so much under supervision as milch-cows, whose 
daily walks are usually restricted to certain fields, have so few 
opportunities of coming in close contact with similar animals 
of another herd unobserved, render them good subjects for 
tracing the source from which an infectious disease is primarily 
imparted to them. Yet in three cases only, Farms 9, 15, and 
16, have the owners been able to attribute a possible source of 
first infection, though all firmly believed their subsequent losses 
to be due to infection only. Let us carefully enquire into the 
circumstances on which they founded their opinions. 
In October 1877 or 1878 the cows of INIr. T. D. (Case 9) 
strayed on to the adjoining farm (No. 11), and remained there 
an uncertain time in company with the cows belonging thereto ; 
it might have been an hour or two, or perhaps for a few minutes 
only. In a few days one of the straying cows aborted, and was 
immediately isolated ; the others were taken up later in October. 
During the two following seasons every cow and heifer on the 
farm aborted. This assuredly has the appearance of an infec- 
tious malady ; but since that time, six or seven years ago, Mr. 
T. D. has had two or three abort annually which have not been 
separated from the others. The last occurred in ]March 1885. 
She was in a building with three companion in-calvers, each 
of which went their full time, though she remained in close 
proximity with them. Surely, if there was sufficient infection 
hanging about this building to cause this cow to abort, we 
should naturally expect it to be so increased by her emanations as 
to cause some or all of her companions to be similarly affected. 
^sow for the reputed source of infection. Mr. J. H. (Farm 11) 
was on the farm nineteen years, during which time he had about 
six cows abort at intervals. He is quite sure he never had two 
or three in quick succession ; they were not isolated. He does 
not remember the circumstance of ^Ir. T. D.'s cows getting to his ; 
consequently he is unable to say whether any of his cattle had or 
had not recently aborted. Assuming there was a recently-aborted 
cow in the herd of Xo. 11, and that such a cow was capable of 
producing specific abortive germs, would not her companions 
who were in constant association with her be more likely to be 
affected by such germs, than the strangers who were only a 
short time in the field? Yet they remained healthy. Then 
again, the two or three per year at intervals, on Mr. T. D.'s 
