200 



STEONGYLUS OVIS-PULMONALIS, Diesing. 

 Plate XXXIII. 



Fig. 1. Section of lung tissue through two small tumors caused by the worms X20 : 

 a, caseous degeneration of tissue in the renter of the tumor ; b, the same 

 in the pathway of the moving, growing worm ; c, cut fragments of the worm 

 (the pathway of the worm is interrupted between a and b, because the plane 

 of the section did not include it) ; d, a bronchus into which the parasite has 

 almost found its way ; e, portion of a second tumor made by another worm ; 

 /, nearly normal tissue. 



Fig. 2. Section through an older tumor at the stage which has been likened to pneu- 

 monia, x20 : o, tumor with fragments of worms; 1>, fragments of an adult 

 worm; c, eggs in segmentation stage ; (f, embryos somewhat developed; e, 

 young embryos; /, bronchi; g, nearly normal tissue. 



Fig. 3. An enlargement of b, Fig. 2, showing fragments of adult worm in the bron- 

 chi and alveolse. 



Fig. 4. An.enlargement of e, Fig. 2, showiiig young worms in the alveolse. 



Fig. 5. An enlargement of c, showing segmenting eggs iu alveoli. 



Fig. 6. An enlargement of d, showingd eveloping embryos in alveoli. In Figs. Sand 

 6 the outlines of the egg-shells are not shown. Figs. 3-6, x90. 

 (These illustrations were made from specimens selected from a number of serial 

 sections which were stained with alum-carmine; the dots represent the 

 nuclei of the cells. All sections show the great multiplication of cells 

 about the points of irritation, whether excited by the adults or embryos.) 



Fig. 7. o, embryo of Strongylus filaria, and b embryo of S. ovis-pulmonaUs, each equally 

 enlarged to show comparative differences iu size and outline. 



