Hog Lung-Worms 265 
A PRELIMINARY REPORT ON HoG LUNG-WORMS. 
GEORGE ZEBROWSKI. 
The work covered in this report comprised a series of experiments 
on the habits and life history of the common hog lung-worms, Metas- 
trongylus apri and Metastrongylus brevivaginatus. This work is still 
being continued, and its object is three-fold: first, to determine the 
morphology and habits of these parasites; second, the life history; 
third, to discover if possible, some practical means of control. The 
first two points are mainly covered in this report. The third point, 
and parts of the life cycle are yet to be completed. These experiments 
are submitted at this time with the hope, that being largely original, 
they may prove of value to other workers in this field. 
The above parasites are of common occurrence in the lungs of 
Indiana hogs. By different investigators, these same species have been 
reported from every country where hogs are kept, hence, there is little 
doubt as to their world-wide distribution. Until recently little work 
has been done with these worms, especially as regards their habits and 
life history. Belief is still current that they are of minor economic 
importance, due no doubt, to their small size and general prevalance. 
However, it was observed, in the examination of several hundred lungs, 
that the number and extent of pathogenic lesions varied directly with 
the number of these parasites present. The very consistent results 
in this respect, led to the inevitable conclusion that these parasites 
must be considered of much greater importance in swine economy, than 
has hitherto been the case. 
In the literature on this subject many conflicting terms are used 
to designate these parasites. Thus Strongylus paradoxus, and Strongy- 
lus apri, are two of a number of synonyms for Metastrongylus apri. 
This form is also confused with another species of common occurrence, 
namely, Metastrongylus brevivaginatus. In Indiana hogs these species 
occur in approximately equal number. The chief characteristics by 
which they can be distinguished are the bursa and spicules of the 
males. In M. apri, the bursa is bilobate and each lobe is sustained 
by five costae. The two spicules are very long and slender, and each 
terminates in a single barb. In M. brevivaginatus, the bursa is less 
campanulate, and each spicule terminates in two hooks. These spi- 
cules are much shorter, averaging only 1.25 mm. in length. The body 
of this species is also longer and stouter than is the case in M. apri. 
In these experiments M. apri is chiefly considered, although, in general, 
such conclusions as are drawn can apply to both species. 
The most recent classification ascribed to these parasites is the 
following: 
1. Phylum; Nemathelminthes. 
2. Class; Nematoda. 
3. Family; Strongylidae. 
