278 Proceedings of Indiana Academy of Science 
attained a week’s growth within the soil, could be found in the mucous 
of the entire respiratory tract. Where two or more lesions occurred 
in a single lung, one was invariably found that was older than the 
rest. Such a typical old lesion was hard and watery to the touch, 
and when cut open, was found to contain numerous granules among 
which were the disintegrated bodies of adult worms. The suggestive 
thing is that a lesion of this kind always occurred at the lowest part 
of the lung, and the secondary lesions were scattered along branches 
of the same bronchus in which the older lesion was found. These con- 
ditions could be explained on the theory that the adult worms secrete 
toxic substances which cause an accumulation of lymph, that eventually 
kills them. The partly developed larvae, being active and resistant, 
make their way along the course of the bronchus until they lodge at 
the terminus of one of its branches. Here they begin to feed and grow, 
producing a new lesion light pink in color and of a dry, puffy nature. 
There seems to be no reason why sexual maturity could not be attained 
within the lung in this manner, and by this means the progeny of a 
single worm could infest an entire lung. 
MOopDES OF INFECTION. 
The next question that suggests itself is, “How do these parasites 
gain ingress into the lungs?” Experimental proof is available to show 
that there are at least two methods. The rats already mentioned were 
given these larvae smeared on bread, in combination with which they 
were readily eaten. Most of these larvae subsequently passed out with 
the faeces, but apparently enovgh resisted the action of digestive fer- 
ments to find their way into the lungs, where they produced the char- 
acteristic lesions. Another experiment, conducted with three pigs to 
which these worms were fed in slop, gave very definite, positive results. 
These results are given in the appendix. 
An additional mode of infection could be by inhaling the larvae as 
dust. For example, when the sweepings of a hog house, in which af- 
fected hogs were kept, were shaken up in a jar of water and allowed 
to stand over night, numerous, active larvae were found in the sedi- 
ment, similar in all respects to those under discussion. The experi- 
ments on dessication further strengthen this theory, for, some of the 
larvae could be revived in fifteen minutes after they had undergone 
drying for a period of six days. The mucous of the nasal passages 
would be an excellent place for these dessicated parasites to lodge, and 
to continue their development. 
PREVENTIVE MEASURES. 
To effectively control these parasites prevention rather than cure 
must be the chief end in view. The common practice of continually 
raising hogs on the same piece of ground, can only result in a heavy 
infestation of the soil in all kinds of parasites. Changing the site 
of the hog lot every two or three years would certainly reduce this 
infection to a minimum. Experiments with the culture plots have 
shown that a heavy application of lime, is very effective in killing these 
parasites. In none of the plots which were subject to this treatment 
