GENUS: HEXAMITA 687 



and a pointed posterior end, the latter being subject to changes in shape. 

 In the small intestine of mice, the forms seen are 4 to 7 microns in length 

 by 2 to 3 microns in breath. In the caecum, longer and broader forms 

 occur, which may measure as much as 10 microns by 5 or 6 microns. The 

 latter may be adult forms of those found higher up in the intestine. From 

 the anterior end arise six flagella in two groups of three (Fig. 288, i). 

 From the posterior end arise two flagella. In stained films it will be seen 

 that the axonemes of the anterior flagella arise from two closely applied 

 granules, each of which appears to be a compound structure composed of 

 four blepharoplasts. From each granule there passes backwards a band- 

 like structure, the axoneme, which is continued into a posterior flagellum. 

 The axonemes of Hexamita are often referred to as axostyles, but there 

 seems no reason to suppose that they are homologous with the axostyle 

 of Trichomonas. In Hexmnita, the axonemes usually stain deeply, while 

 in TricJiomonas the axostyle does not readily stain. It has been suggested 

 by Kofoid and Swezy (1915a) that the axostyle of TricJiomonas represents 

 the axoneme of a backwardly directed flagellum, as in Hexamita. At the 

 anterior end of the body of H. muris, and just behind the blepharoplasts, 

 are two nuclei, between which the axonemes pass. Very frequently the 

 nuclei, blepharoplasts, and anterior parts of the axoneme stain as a single 

 compact and lobed mass, so that there is difficulty in distinguishing the 

 separate parts {cf. Fig. 287). 



Multiplication of H. muris takes place by longitudinal division 

 (Fig. 288, 2-4). There is division of the blepharoplasts and nuclei, and 

 with it division of the axonemes, so that there are produced rounded 

 bodies with four nuclei and four axonemes. Presumably, by division 

 of the body into two parts, two daughter individuals, each with two 

 nuclei and two axonemes, are formed. Dobell (1909) has expressed it 

 as his opinion that the division stages of H. muris, figured by Foa (1904) 

 and by the writer (1907), were degenerate and fused forms which have 

 nothing whatever to do with division. This is certainly not the case. 

 Very similar division forms have been seen by Alexeieff (1908) and Swezy 

 (1915) in species of Hexamita from amphibia (Fig. 290). 



The encysted stages of H. muris also occur, and can be found in the 

 caecum. These are elongate bodies with rounded ends (Fig. 288, 5-6). 

 They measure 6 to 7 microns in length by 3 to 4 microns in breadth. In 

 stained films the cyst can be seen to contain a single flagellate. In some 

 cysts, nuclear division has taken place, so that four nuclei are present. 



If faeces of mice which are known to contain H. muris are diluted 

 with water, cultures of this flagellate may be obtained. This seems to 

 suggest that the forms which are found in stagnant water may actually be the 

 same species as those which live in the intestine of amphibia and rodents. 



