132 RESEARCH IN PROTOZOOLOGY 



tions. This cloud-like chromatic area may represent material com- 

 parable to the chromatic granules of T. parva which has not be- 

 come organized into discrete granules. 



The parabasal body. A great deal of confusion exists as to the 

 nature and function of the structures to which this term has been 

 applied. In the trichomonads the parabasal appears to be dissolved 

 by certain fixatives (e.g., Schaudinn's fluid) and to be preserved 

 by others (osmic acid and certain of its mixtures). Duboscq and 

 Grasse (1925) call attention to the heterogeneous nature of the 

 parabasal and Grasse (1925) suggests that it may have a secretory 

 function. Boeck (1919) believed that the parabasals of Giardia 

 (which are not dissolved by Schaudinn's fluid) secrete glycogen, 

 a reserve food supply utilized during the reproductive period and 

 during encystment. Further study will doubtless show that the 

 functions of the parabasal bodies are somewhat different in differ- 

 ent flagellates. 



CYTOLOGY AND LIFE HISTORY 



The life history of none of the flagellates of rats has been com- 

 pletely worked out. The trophozoites, the dividing animals and 

 the cysts are the only stages definitely known. Division is usually 

 of the binary type but may be multiple. Both types of fission may 

 occur in the active state or in the cyst. 



I. Binary and multiple fission 



Binary fission has been described for Tritrichomonas mmris in 

 considerable detail (Wenyon, 1907; Kuczynski, 1914, 1918; 

 Kofoid and Swezy, 1915; and Wenrich, 1921). In the active state 

 fission is accompanied by a mitotic division of the nucleus during 

 which six double or split chromosomes form and divide while the 

 karyosome gradually fades out. The behavior during division of 

 the parabasal body, the chromatic granules and the cytostome has 

 not been followed in detail. 



Binary fission has not been worked out for any of the other 

 trichomonads of the rat. However, the writer noted in 192 1 that 

 T. minuta, which resembles T. muris in most respects except in 

 size, appears to have only three chromosomes in division. The idea 

 that T. minuta may be a haploid race of T. muris has suggested 

 itself and should be investigated. 



Division of the nucleus by mitosis and the definiteness and con- 



