ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 599 



distinctly hyaline ; it does not take up any colouring matter, and is, to 

 all appearances, produced by the tissue of the host. The median capsule 

 appears to be made up of separate strong plates, laid down somewhat 

 irregularly, and having fine ducts between them ; this capsule stains 

 very intensely with anilin-dyes. The internal capsule is the thinnest, 

 and like the other two is transparent ; it does not stain with carmine or 

 anilin. Treatment with iodide of potassium and sulphuric acid shows 

 that the median capsule consists of true cellulose, and it may be, therefore, 

 that the parasite is a plant and not an animal. 



Megastoma entericum.* — MM. B. Grassi and W. Schewiakoff have 

 an account of the structure of this protozoic parasite of mammals. The 

 latter author is alone responsible for the views enunciated as to the 

 systematic position of the animal. He believes it to be closely allied to 

 Hexamitus infiatus Duj., and to Giardia agilis of Kiinstler. They agree 

 essentially in the arrangement of the flagella, but Megastoma is dis- 

 tinguished by the development of its peristome, which has brought about 

 some change in the place of insertion of the flagella, and in the form of 

 the nucleus. 



The parasite has been found in a number of Eodents, and in Cats, 

 Dogs, and Sheep. It lives chiefly in the duodenum and jejunum, and is 

 found encysted in the colon. By means of its peristomial excavation it 

 attaches itself to the epithelial cells of the villi, at the cost of which it 

 lives ; while it is dangerous as preventing normal absorption. From the 

 observations of Grassi it appears probable that Megastoma may produce 

 diarrhoea and anemia in man. 



* Zeitschr. f. Wiss. Zool., xlvi. (1888) pp. 143-54 (1 pi.). 



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