SEX IN PROTOZOA 145 



supposed ro be ganionts or gametes of T. congolense. Also, "latent 

 bodies" were said to form after sexual union, and these contained one 

 or two nuclei and six chromosomes. 



Roskin and Schischliaie\\'a (1928) described mitoses with only 

 three chromosomes, not only in T. congolense but also in T. equiper- 

 dinn, T. briicci and T. ''surra,''' and Wolcott (1952) found only three 

 chromosomes in T. leivisi. In many protozoan nuclei the prophase 

 chromatids often become rather widely separated so that the chro- 

 mosome number appears to be double that shown in the metaphase 

 and anaphase. Thus the condition of two paired and two unpaired 

 chromosomes reported by \^anderplank may well be a prophase stage 

 show ing three pairs of chromatids, two of which are somewhat more 

 separated than the others, and the combination of two pairs and one 

 unpaired might well be a case where the chromatids were visible for 

 two of the chromosomes and not well separated for the third. 



Fiennes (1945) also reported sexual phenomena for Trypano- 

 soma congolense. Developmental forms were found in sections and 

 smears from the skin of infected cattle. T. congolense was stimulated 

 to "conjugate" by adding a drop of 0.3% sodium chloride to a drop 

 of mouse blood containing the flagellates; micro- and macrogametes 

 w ere said to develop from sexually mature forms and fuse within 

 10 minutes. A "microgamete" penetrated the translucent posterior 

 region of a "magrogamete," the posterior end entering first. The 

 "zygote" thus formed was about 20 v- long and motile, with try- 

 panosome shape, but contraction of the body produced an "oocyst" 

 about 10 [i. in diameter. The "oocyst" appeared to form "sporoblasts," 

 probably eight in number, which divided into many "sporozoites." 

 The fate of these "sporozoites" was uncertain. Trypanosomes in 

 mouse blood treated with weak salt solution showed three different 

 forms: (1) immature sexual or asexual stages which showed no 

 changes except swelling; (2) mature sexual stages which united as 

 described; (3) infective (?) forms which were changed into a variety 

 of developmental stages, round, stumpy, elongate, and so on, usually 

 found in the tsetse fly. The predicted confirmatory papers have not 

 been seen. 



Fairbairn, Culwick, and Gee (1946) reported syngamy in Try- 

 panosoma rhodesience and T. simiae. Metacvclic forms of T. rhode- 

 siense occurred in two distinct types with significantly different 

 mean lengths. These two types produced three blood types, long. 



