TKICHOMONAS HOMINIS 651 



Bohne and Prowazek (1908) described a Blastocystis as being the cyst of 

 T. hominis, and sujjposed that this encystment was associated with a 

 process of autogamy. Several writers, including Bensen (1909), claim to 

 have confirmed this observation. There is no doubt, however, that Blasto- 

 cystis, a vegetable organism which can be cultivated, has no connection 

 whatever with T. hominis (Fig. 118). The cysts described by Lynch (1916) 

 are so similar to the cysts of Chilomastix mesnili that they cannot be 

 regarded as cysts of T. hominis till further evidence has been produced. 

 Lynch (1915c) described, both from faeces and cultures, spherical cysts with 

 granular contents, but from the description it is impossible to conclude 

 that he was dealing with encysted Tricho^nonas. They did not show any 

 of the characters of the encysted forms as seen in animals. In a later 

 paper this author (1922) admits that cysts of T. hominis have not yet been 

 discovered. 



T. hominis reproduces by longitudinal division. The process has not 

 been studied in detail in this species, which is usually of small size. As 

 regards the division of other species, there are many conflicting statements 

 as to what actually occurs. In stained films, a few further details of the 

 structure of T. hominis can be made out. The human flagellate is a very 

 small form which easily shrinks on fixation, so that it is exceedingly 

 difficult to make satisfactory preparations. In addition to the various 

 details which can be detected in the living organisms, it can be seen that 

 there is a spherical or slightly ovoid nucleus near the anterior end of the 

 body. It consists of a nuclear membrane surrounding a clear space, at 

 the centre of which is a karyosome. Anterior to the nucleus is a closely 

 packed group of blepharoplasts. From these arise the axonemes of the 

 anterior flagella, and also the one which borders the undulating membrane, 

 as well as a stiff fibre, the basal fibre, which passes through the body just 

 below the attachment of the undulating membrane. Posteriorly, the 

 basal fibre tapers to a point. Parallel and close to it can sometimes be 

 distinguished a row of deeply staining granules. 



The axostyle is another structure which commences at the blepharo- 

 plasts. It has the form of a broad bar which takes a straight course through 

 the body to the posterior extremity, through which it protrudes as a sharp- 

 pointed caudal process. The axostyle, unlike the basal fibre, does not stain 

 black with iron haematoxylin. In the living organism the axostyle is perfectly 

 passive, and only moves with the contractions of the cytoplasm around it. 



T. hominis feeds by ingesting bacteria through its cytostome, and these 

 can be seen in various food vacuoles. It is possible that it also absorbs 

 nourishment in solution through the surface of its body. Sometimes red 

 blood-corpuscles are present in vacuoles. The writer has seen them within 

 T. hominis in cases of bacillary dysentery when many red cells are jjresent 



