CHAPTER VIII. 



THE PATHOGENIC FLAGELLATES- -(CONTINUED). 

 THE GENUS TRYPANOSOMA, GRUBY. 



AT the present day more than sixty species of trypanosoma have 

 been described from different types of vertebrates, and although the 

 greatest difference of opinion exists here, as with spirochetes, it is not 

 in connection with the animal or plant characteristics, but rather with 

 the relationships and life history. Various students of the group, 

 beginning with Leger ('04), have attempted to separate all of the dif- 

 ferent varieties known into distinct groups, according to the morpho- 

 logically "anterior" end. In some the flagellum issues from the cell 

 at the supposedly posterior end, in others at the supposedly anterior 

 end. The former, including all of the piscine trypanosomes, are 

 grouped by Liihe ('00) in a distinct genus, to which he applies Mitro- 

 phanow's name, hematomonas; the latter includes all of the mam- 

 malian trypanosomes to which Lithe gives the distinct generic name 

 trypanozoon, while a third generic name, hemoproteus, is given for 

 the trypanosome of the owl, having a dual life in the serum and in the 

 blood cells, as described by Schaudinn. Woodcock ('06) likewise 

 separates the latter from all other trypanosomes, under the generic 

 name of trypanomorpha. 



The scientific value of these divisions of the trypanosomes stands or 

 falls with their phylogeny and with the terminal homologies of the 

 different species. A typical trypanosome, for example, T. theilerl, 

 Bruce, found exclusively in the blood of cattle, consists of an elongate, 

 more or less serpentine cell body, from one end of which projects a 

 vibratile flagellum (Fig. 97). The flagellum is continued toward the 

 opposite end of the cell as a well-marked marginal cord, and takes its 

 origin from a minute granule (blepharoplast) not shown in Liihe's 

 figure. Near this terminal granule lies a large, deeply staining body 

 of chromatin (&), which in some species is larger than the nucleus, and 

 in others has a typical reticulate nucleus character. In agreement with 

 the views of Schaudinn, Woodcock, Liihe, Minchin, and others, this 

 chromatin or nucleus-like body will be designated the " kinetonucleus," 

 a term suggested by Woodcock ('06) because of its close connection 

 with the motile elements of the cell (see p. 33). Between the attached 

 part of the flagellum and the body is a delicate protoplasmic mem- 



