TRYPANOSOMA RHODESIENSE 77 



blepharoplast or kinetic nucleus (fig. 31,4, 5). When the nucleus was 

 beside the blepharoplast, the former was seen to be kidney-shaped 

 (fig. 31,4). The posterior nuclear forms were of the stout and stumpy 

 variety, and about 6 per cent, of the stumpy forms were found to have 

 their nuclei displaced from the centre. The anterior or flagellar end 

 of these trypanosomes often contained chromatoid granules. T. 

 rhodesiense varies in length from 12 p to 39 yu, 1 ; short stumpy forms 

 vary from 13 p to 21 //,, intermediate forms from 21 p to 24 //,, and long, 

 slender forms from 25 /JL onwards. The average length is 24*1 //,. 



Certain regular periods occur in the course of the trypanosomiasis 

 when few or no flagellate trypanosomes are found in the peripheral 

 blood of the patient or of the sub-inoculated animal. These periods 

 can be explained in terms of morphology, for the trypanosomes are 



FIG. 31. Trypanosoma rhodesiense. i, Long narrow form; 2-4, nucleus passing to 

 posterior (aflagellar) end ; 5, nucleus quite posterior, x 1, 800. (After Stephens and Fantham.) 



capable of assuming a non-flagellate form in the internal organs of the 

 host, particularly in the lungs and in the spleen. Such forms are 

 known as "latent" or "resting" forms. The term "latent body" 

 was first used by Moore and Breinl in igof in connection with 

 T. gambiense. Fantham 3 (1911) has described the process of forma- 

 tion of latent from motile forms and the reconversion of the latent 

 bodies into active flagellates. Fresh preparations of splenic blood 

 or lung blood containing trypanosomes were made. A trypano- 

 some gradually withdrew or cast off its flagellum, concentrated its 

 cytoplasm, and became more or less elongate oval. Nucleus and 

 blepharoplast approached one another and came to lie more or less 

 side by side. Then an opaque line often made its appearance around 

 the nuclear area and differentiated as a slight envelope or covering, 

 the cytoplasm external to this merely degenerating. The small, oval, 

 refractile body (fig. 29, d f) thus formed was a non-flagellate latent 

 body, 2 /x to 4 /A in diameter, like Leishmania or the non-flagellate, 



1 Stephens and Fantham (1912-13), Proc. Roy. Soc., B, Ixxxv, p. 223, and Annals Trop. 

 Med. and Parasitol. , vii, p. 27. 



Annals Trop. Med. and Parasitol., i, p. 441. 3 Proc. Roy. Soc., B, Ixxxiii, p. 212. 



