376 
The Lung Parasites of Cattle and Sheep. 
would at least bear some general resemblance to the young of 
the cattle lung-worm. Here, therefore, is one point to be 
settled bj future investigation. Again, as regards the possi- 
bility of the larvae being swallowed by animals during the act of 
drinking, it is easy to understand how a brisk shower of rain 
might wash the tiny larva? from off the blades of grass or other 
herbage into ditches and ponds. However, I suspect that it is 
not by the act of drinking that the larvae are ordinarily trans- 
mitted to animals. No doubt, many persons are firmly of 
opinion that it is by the act of drinking, and by that alone, that 
infection occurs. Thus, when, in 1875, Mr. George Farrow, V.S., 
sent me the lungs of a calf for experimental purposes, he stated 
that the dead animal which furnished the organs in question was 
one of a herd of seven whose ages, respectively, varied from four 
to six months. At the time of his writing, the remaining six 
animals were progressing favourably towards recovery ; a result 
which Mr. Farrow attributed to the employment of inhalations 
of turpentine and savin, combined with the administration of 
tonics. Mr. Farrow added : " The cattle are on a very dry and 
well-drained farm, but during the summer there was a great 
scarcity of water, and they were supplied from a stagnant pool, 
which eventually became dry. Tliis, in my opinion, is ivhere the 
disease originated.'^ Mr. Farrow may be quite right ; but, me 
judice, it is more likely that the disorder arose from the nibbling 
of the calves, or their attempts to graze in the immediate vicinity 
of the ponds. Be that as it may, the methods of exact research 
alone can finally settle the question of the mode of entry. As 
regards the life-history of the parasites, it is, perhaps, of little 
moment whether the views I have here set forth be confirmed or 
not. At all events, until they receive verification, I am wholly 
disinclined to dogmatise upon the matter. Oft-repeated, con- 
tinuous, and sustained observations on a larger scale are neces- 
sary. The most favourable periods of the season for commencing 
fresh investigations are towards the close of the summer and the 
early weeks of autumn. 
