442 J. A. Gilruth and L. B. Bull : 



the high power is seen to be distributed in true papillomatous 

 fashion, sending into the lumen of the intestine long processes 

 cariying the hypertrophied villi. These villi in turn are greatly- 

 distorted by the presence of large numbers of parasitic cysts 

 (Plate LXXX.. Fig. 16), which differ from any of those previously 

 described. These cysts are generally attached to the surface of 

 the villi, which are otherwise denuded of epithelium, but here 

 and there they are to be found crowding and distending the 

 glands of Lieberkiihn when they are surrounded by more or 

 less new inflammatory tissue (Plate LXXX., Fig. 17). In none of 

 the sections made from different parts of the intestine are 

 mature cysts seen. On the contrarv^ by far the greater number 

 are evidently degenerated, the contents consisting simply of a 

 oranular homoo-eneouslv staining material. That this degenera- 

 tion is not due to the lapse of time after death of the host before 

 the tissue was fixed is evident from the irregular distribution of 

 the living and degenerated cysts (Plate LXXX., Fig. 17, and Plate 

 LXXXVIL, Fig. 18). In both cases there is often considerable 

 shrinking of the cystic contents from the wall which is more 

 definite in the degenerated cysts than in the others, and may be 

 to some extent due to fixing. The living cysts which are usually 

 the larger are composed of a thin envelope and an endoplasm, 

 containing many small nuclei (0.85/a to 1.48/x). Tliey are 

 spherical or ellipsoidal, measuring from 0.093 mm. to 0.113 mm. 

 in greatest diameter. The envelope is thin and shows no brush- 

 like arrangement, and in few can any remains of an original 

 cell nucleus be determined. The endoplasm consists of a homo- 

 geneous or faintly granular material, staining with eosin and 

 such stains, amongst which in the earliest stages observed are 

 scattered the minute deeply staining nuclei. These nuclei may 

 be arranged without apparent order, but are usually grouped 

 around masses of the protoplasm, and appear as circular, oval, 

 and at times reticulated areas. No further stage of development 

 has been detected in any of our sections. 



As the cyst increases in size it should be noted that the 

 nuclei become smaller and more irregularly arranged, so much 

 so that the largest cysts consist of a very thin ectoplasm, con- 

 taining minute cocci (0.8/a in diameter). 



