MASTIGAMCEBA—MASTIGELLA— MASTIGINA 267 



with the Rhizopoda, and not with the Mastigophora, because they live 

 mostly as amoebae and crawl about by means of pseudopodia, instead of 

 swimming by means of their flagella. Unlike the members of the family 

 DimastigamoebidsB, they retain the flagellum throughout the amoeboid 

 phase. There are three genera. The genus Mastigamoeha includes large 

 amoebae with a flagellum as long as, or longer than, the body. The 

 axoneme of the flagellum arises from the nuclear membrane. The genus 

 Mastigella includes similar forms, in which the flagellum is unconnected 

 with the nucleus. The genus Mastigina comprises amoebae which have 

 a short flagellum, the axoneme of which arises from the nuclear membrane. 

 The majority of these forms are free living, and for one of these Goldschmidt 

 (1907) described a complicated life-cycle, which, however, has not received 

 confirmation. A few parasitic forms have been described. Frenzel (1892) 

 described as Tricholimax hylce a flagellated amoeba from the intestine of 

 tadpoles of the genus Hijla in the Argentine (Fig. 73). Goldschmidt (1907) 

 placed it in the genus Mastigina. Collin (1913) studied this organism, 

 Mastigina hylcB, in tadpoles of newts and Bufo calamita in Europe. 

 Spherical cysts, 25 to 28 microns in diameter, were produced, and these 

 contained two or four nuclei. What was possibly the same organism 

 was seen by Hoare, working in the writer's laboratory, in the intestine 

 of Triton vulgaris in England. Becker (1925) has seen it in tadpoles of 

 Rana clamata and R. cateshiana in America. He notes that the single 

 short inactive flagellum arises from a blepharoplast situated on the nuclear 

 membrane, and at one end of a cap-like structure which partially covers 

 the nucleus. From the whole surface of the cap radiating fibres pass into 

 the cytoplasm. From the blepharoplast a deeply staining curved rod 

 passes into the cytoplasm. It is homologized with the basal fibre (rhizo- 

 style) of the membrane of Trichomonas. Becker sees in the structure of 

 this organism a ground plan of the morphology of such flagellates as 

 Trichomonas, Chilomastix, and even Giardia. 



Another parasitic form is that described by Liebetanz (1910) as 

 Mastigamoeha bovis from the rumen of cattle. It measures about 

 25 microns in longest diameter, and is provided with a flagellum about 

 twice as long as the body. The cytoplasm is dift'erentiated into a well- 

 marked ectoplasm and endoplasm, and there is a large central nucleus. 



