PARASITES OF ANIMALS. 129 
and thus pass them with the feces. In either case they will. 
often adhere to grass and other herbage, and may thus be 
swallowed by other sheep or lambs, fed in the same pastures, 
and pass directly into the windpipe, or clse do so when the 
cud is raised for mastication. Therefore lambs should never 
be put into fields or pastures where diseased animals have 
been kept, but such infected lands should be tilled, or at least 
left at rest for several months. As soon as an animal gives 
any indication of the presence of the parasites by the 
peculiar cough. it should be separated from the rest of the 
flock for treatment: or else immediately killed and the para- 
sites should be effectively destroyed. and not thrown on the 
ground as harmless, for all these worms are remarkably 
tenacious of life, and often may even be dried up completely 
for months, and then revive when moistened. 
Remedies. 
When these parasites are once lodged in numbers in the 
substance of the lungs. there is probably no reliable remedy 
whatever. When merely in the windpipe and bronchial tubes. 
expectorant medicines that will produce a copious secretion 
of mueus may be useful. It might be possible to remove 
them by a surgical operation, opening the windpipe from the 
exterior, but this would require surgical skill and would not 
pay. perhaps, except as a last resort for valuable animals. 
The Strongylus of Cattle and Horses (Strongylus micrurus 
Mehlis). 
This species closely resembles the preceding. The male 
grows to the length of about one inch and a half; and the 
female to three inches or a little more. The body is very 
slender-with a simple, blunt head. The bursa of the male 
has five rays. The female eenital orifice is near the middle 
of the body. It is said to be viviparous. 
The habits of this species are nearly the same as those of 
the last. except that this inhabits the air-passages of cattle, 
horses. asses. and mules. instead of sheep. It is much more 
liable. like the former, to infest young animals than adults. 
Calves less than a year old are particularly liable to be in- 
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