296 



FAMILY: MONADIDiE 



spends in every way with Sphceromonas communis described by Liebetanz 

 from the rumen of cattle (Fig. 139). There seems, therefore, to be no 

 doubt that Kofoid and Swezy have discovered a small uniflagellated 

 organism in human fseces. The fiagellum cannot be detected in every 

 one of the organisms, but when it is present it arises from a granule 

 near the surface of the parasite, while a fibre is depicted as connecting 



.^ this granule with the centrally 



r 



/ 



A 



^ 



^ 



^i-?^ 



o 



Fig. 140. — BhizomasUx gracilis Alexeieff, 

 1911, FROM Intestine of Larva of Tipula 

 sp. ( X 4,000). (After MACKINNON, 1913.) 



A. Flagellate form. 



B. Cyst with one nucleus. 



C. Cyst showing nuclear division. 



D. Cyst with two nuclei. 



placed karyosome of the nu- 

 cleus. In its course it passes 

 through the nuclear membrane. 

 Spherical cysts which contain a 

 uninucleated cytoplasmic body 

 and resemble the cysts of some 

 free-living amoebae also occur. 

 The discovery of such a form 

 does not in any way establish 

 the authenticity of the genus 

 Craigia. Kofoid and Swezy 

 state that they have seen their 

 organism in six cases. It is 

 possible that, owing to the ex- 

 treme fineness of the fiagellum 

 and the difficulty of detecting it 

 exceptin well-stained specimens, 

 this organism has sometimes 

 been mistaken for Endolimax 

 nana, to which it bears a super- 

 ficial resemblance. On the other 

 hand, th e possibility of its bei ng a 

 coprozoic flagellate of the genus 

 Oikomonas which has developed 

 in the fseces after they have left 

 the body has to be considered. 



Gemis 



Rhizomastix Alexeieff, 



1911. 



The flagellates of this genus 



have rounded or pear-shaped 



bodies and a central nucleus. 



There is a long flagellum arising from the anterior end of the body, and 



its axoneme is continued into the cytoplasm in the form of a long fibre 



which terminates in a blepharoplast behind the nucleus. 



