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intestine, becoming ciliated, and having also similar staining reaction. 

 The staining reaction of the bulk of the diverticulum is quite different 

 from that of the epithelial lining of the intestine, from which it orig- 

 inates. At the point of union of the diverticulum with the digestive 

 tract there is a marked and abrupt increase in the diameter of the 

 latter. 



A comparison of the structure of these organs with that of the 

 corresponding organs of H. niodcrata reveals a wide difference in the 

 two species. In the latter a totally different plan of structure is found. 

 It is not possible to make extensive comparisons owing to the meager 

 treatment of the intestinal diverticula in the literature of other species 

 of Henlca. Michaelsen ('86a) figures their structure in H. leptodera 

 Vejd. and H. ventriciilosa Udek., and both conform to the same 

 general plan as that presented in H. iirbanensis. They have one rather 

 spacious central internal cavity bounded by walls which show in fold- 

 ings, and which contain the blood sinuses in somewhat the same re- 

 lation. However, they are quite different from those of H. urbanen- 

 sis as indicated by the following facts :- H. ventriciilosa has four 

 diverticula, which, alone, distinguishes it from the other species. H. 

 leptodera has two diverticula, but they differ from those of H. ur- 

 banensis since the folds in the inner lining are larger, and though 

 much fewer in number are present on the ental as well as on the ectal 

 wall. The branches of the blood sinus are also fewer. Michaelsen 

 ('89) described and figured the structure of the intestinal diverticu- 

 lum in H. nasuta, which also presents the same general type of struc- 

 ture as in H. iirbanensis but has wider and more irregular folds of 

 the lining membrane. The folds also show branching — a condition 

 which does not appear in H. iirbanensis. Furthermore, according to 

 Michaelsen's figure there is in H. nasuta no difference in the structure 

 of the ectal and ental walls. The distribution of the blood sinuses is 

 somewhat similar. Eisen ('05, p. 100) makes the following brief 

 statement concerning these organs in H. calif ornica: "Intestinal 

 pouches in VII are similar to those figured by Michaelsen from 

 H. nasuta. The villi are fully as intricately folded." The same 

 writer ('05, p. 102) makes the following meager statement concern- 

 ing H. gnatemalce : "Intestinal pouches in VII ; epithelium with com- 

 paratively few folds;" and, again, concerning H. ehrJiorni he says 

 ('05, p, 105) : "Intestine. — The tubular part is furnished in VIII 

 with a pair of diverticles which not only fill the largest part of VIII 

 but also project into VII. The inner lobes of the diverticles are much 

 coarser than in H. calif ornica, the villi being less numerous and more 

 of the nature of those of the diverticles of Benhamia. At the pos- 



