PROTOZOA 



401. 



the wild ruminants of Zululand. The parasites become in- 

 active and soon die after the death of the host. 



Morphology. Tr. Brucei appears in fresh blood as a small 

 very motile organism, with a spiral like 

 body having an undulating membrane 

 and flagellum. It usually moves with 

 the flagellar end foremost, so that this 

 is regarded as the anterior extremity. 

 The organism has approximately the 

 same size in the rat, mouse, guinea pig 

 and dog, i. e. from 25 to 27 /x long and 

 from 1.5 to 2.5 ju, wide. In the horse and 

 donkey it is longer, measuring from 28 

 to 33 /x in length. When the blood is 

 centrifuged, the parasites are found 

 most abundantly in the upper part of the 

 layer formed by the red corpuscles. This 

 method is recommended in searching for 

 trypanosomes when they are present in 

 small numbers. Small bodies have been 

 observed in the lymph glands, in the 

 bone marrow and in the spleen which 



vary from 1 to 2 /* in diameter. Fi ^ 88 ' Trypanoso- 



. . . -^ ... j? i ma Brucei from rat's 



Staining. For staining fresh prep- Wood (After Nocht 



arations of this species neutral red, to- and Mayer). 



luidin blue, and methylene blue stain the 



granules in the interior of the living 

 trypanosome. The stain becomes 

 more general with preparations of 

 dead organisms. 



Novy and McNeal 2 succeeded in 

 cultivating Trypanosoma Brucei and 

 Tr. Lewisi. The former is more sensi- 

 tive and more exacting in its cultural 

 requirements than Tr. Lewisi. Tr. 



(After Nocht and May- Lewisi will grow on a medium con- 



er). taining one-half or less of its own 



2 Novy and McNeal. Jour, of Inf. Diseases, Vol. I (1904) p. 1. 



Fig. 89. Trypanosoma 

 Brucei in blood of a rat. 



