PARASITES OF ANIMALS, 327 
it under different heads, grouping together those animals 
which harbor the same species of worm. 
Verminous bronchitis in the ox, horse, ass, and mule.—The 
same parasite attacks one and all of these animals. This is 
the Strongylus micurus of Mehlis, a small, thread-like worm, 
the male one and a half inches long, the female three inches. 
The head is rounded, with no constriction or neck, the mouth 
furnished with three chitinous papille, the cesophagus club- 
shaped, the genital orifice of the female situated in the ante- 
rior half of the body, and the tail pointed: the male has a 
caudal pouch with five rays standing well apart. They were 
noticed by Camper to be viviparous, but this must be qualified 
by the statement that the female, after becoming imbedded in 
the lung substance, or after being expelled by coughing, per- 
ishes often with its oviducts still full of ova, and these gradu- 
ally hatch out amidst the decomposing debris of the parent. 
Development.—The development of the parasites has to be 
considered as it takes place im and out of the body. Within 
the body in the earlier stages of their life—that of ova and 
embryos—the parasites are found imbedded in the substance 
of the lung-tissue, mostly toward the margins of the lobules, 
where they may live for indefinite but often long periods. 
Baillet killed a lamb thirty-two days after he had administered 
the embryos of a Strongylus filaria taken from the oviducts of 
a female worm, and found the parasites rolled up into pellets 
in minute semivitreous nodules in the posterior part of the 
lungs, and varying in length from one-third to aline. It is prob- 
able, therefore, that these lung-infesting strongyli may live for 
many months encysted in the pulmonary tissue in this imperfect 
condition. The appearance of the lung so affected is redder 
than natural, and its surface feels rough and uneven by rea- 
son of the numerous exudations around the embryo worms. 
These nodules, which were long mistaken for miliary tuber- 
cles, vary in size from that of a pin’s head to that of a barley 
corn, while at certain points many will become accumulated 
so as to cause uniform consolidation of lung-tissue to a con- 
siderable extent. They vary, too, in consistency from a sim- ~° 
ple semifluid mass to a hard calcareous shell. The soft and 
