546 TRYPANOSOMIASIS 



as existing ; this has been considered by some to be analogous 

 to the contractile vacuole present in many protozoa, and its 

 shape and position have been made the basis of specific dis- 

 tinctions ; Laveran, however, thinks it is an artefact. From 

 the micronucleus or from its neighbourhood there arises an 

 important structure in the trypanosome, the undulatory 

 membrane. This is of varying breadth, has a sharp undulating 

 free margin, and surmounts the protoplasm of the organism 

 like a cock's comb; it narrows towards the anterior end 

 where it passes into the flagellum. Motion is chiefly effected by 

 the undulations of this membrane and of the flagellum. The 

 latter is continuous with the protoplasm of the body of the 

 organism ; it stains uniformly like it, except the free edge which 

 has the reddish hue of the chromatin. In different species 

 of trypanosomes variations occur in shape, in length, in breadth, 

 in the position of the micronucleus (and therefore in the 

 length of the undulating membrane), in the breadth ,of the 

 membrane, in the length of the free part of the flagellum, in the 

 shape of the posterior end, which is sometimes blunt, sometimes 

 sharp, and in the presence or absence of free chromatin granules 

 in the protoplasm. 



Multiplication in the body fluids ordinarily occurs by 

 longitudinal, amitotic division (see Fig. 168). First of all the 

 micronucleus divides, sometimes transversely, sometimes longitud- 

 inally, then the nucleus and undulating membrane, and lastly 

 the protoplasm. In some species the root of the flagellum only 

 divides so that in the young trypanosomes the flagellum is 

 short and subsequently increases in length (Tr. Lewisi) ; usually 

 the whole flagellum takes part in the general splitting of the 

 organism. 



In the cases of several of the trypanosomata it has been 

 found possible to cultivate them outside the body, the chief 

 work here having been done by Novy and MacNeal, who have 

 succeeded with the Tr. Lewisi, Tr. Evansi, and Tr. Brucei. 

 The most suitable medium is made as follows : 



125 grammes rabbit or ox flesh is treated with 1000 c.c. distilled 

 water, as in making ordinary bouillon, and there are added to the 

 meat extract 20 gr. Witte's peptone, 5 gr. sodium chloride, 20 gr. 

 agar, and 10 c.c. normal sodium carbonate. The medium is placed in 

 tubes and sterilised in the autoclave at 110 C. for thirty minutes. It is 

 cooled to 50 C. , and there is added to the medium in each tube twice its 

 volume of defibrinated rabbit blood, which has been prepared with all 

 aseptic precautions ; the tubes are allowed to set in the inclined position. 

 In inoculating such tubes they are placed in an upright position for a 

 few minutes and then the infective material is introduced. 



