24 Sir D. Bruce and Capts. Hamerton and Bateman. [Sept. 18, 



Nucleus. — Round or oval in shape. Situated centrally or at the junction 

 of the anterior and middle thirds. 



Micro-nucleus. — Is placed either close to the nucleus or at a variable 

 distance anterior to it. In the free forms it is never seen lying posterior to 

 the nucleus. As a rule, it is a rod-shaped structure, lying transversely to the 

 long axis of the trypan osome. 



Flagellum. — Arises from the vicinity of the micro-nucleus. The free 

 flagellum is often two, three or four times the length of the body of the 

 trypanosome. 



Undulating Membrane. — In the cultural form of Trypanosoma lewisi this 

 structure is apparently absent. 



Colonies or Aggregations. — There is little to add to the description of the 

 trypanosomes and of their arrangement in colonies. Stained preparations 

 show that the trypanosomes sometimes possess very long flagella. ISTovy 

 and MacNeal* have not apparently succeeded in staining the flagellum in 

 their preparations, though they noted the position of the centrosome. They 

 expressed the opinion that the end of the trypanosome pointing towards the 

 periphery of the colony was the anterior extremity, and that from it a 

 flagellum would arise if the cultural conditions were perfected (Smedley). 



Measurements of the Cultural Forms of Trypanosoma lewisi. 



Pear-shaped Forms. — (1) Body, 3 '6 to 4 - 4 microns long, and nearly as broad. 

 (2) Flagellum, two to four times the length of the body. 



Spindle-shaped Forms. — 14 to 16 x 2 - 4 to 3 - 5 microns, flagellum not 

 included. 



Smaller and larger forms are frequently found. 



The adult parasitic form of Trypanosoma lewisi measures 24 to 25 x 

 l - 5 microns (Laveran and Mesnil) (Smedley). 



Cultural Characters of Trypanosoma brucei. 

 A. Living, unstained. 



Size. — Shows less variation in size than Trypanosoma lewisi, and averages 

 15 microns in the living condition. Smaller than those found in the blood. 



Shape. — Do not vary much in shape, and closely resemble the forms found 

 in the blood (Smedley). 



Contents of Cell. — Show one or two very large, bright, and highly-refracting 

 globules, usually placed near the anterior or flagellar end, in the otherwise 

 homogeneous colourless cell. In size the globules may attain 1 micron 



* ' Cultivation of Trypanosoma brucei,' p. 28. 



