1908.] 



A Trypanosome from Zanzibar 



17 



tannin 5 per cent., in distilled water). When sufficiently decolorised, the 

 films are washed in distilled water, dehydrated by passing through acetone, 

 cleared in xylol, and mounted in Canada balsam. 



Dr. Edington's trypanosome when stained in this way appears of a pale 

 puce colour with reddish-purple nucleus and micro-nucleus. The following 

 detailed description must be understood to refer to this trypanosome as 

 found in the blood of the white rat. 



Length. — It is no easy matter to measure these small irregularly-shaped 

 bodies, and doubtless the method of measurement used will govern to some 

 extent the result. The method used by us is simply to draw a sharp outline 

 of the trypanosome by means of a Zeiss camera lucida, at a magnification of 

 2000 diameters, and then to measure along the middle line of the body by 

 means of a pair of fine compasses, the points of which are separated 

 2 mm. Each step the compass takes is therefore equal to 1 micron. Twenty 

 trypanosomes, taken as they come, are measured in this way in each 

 specimen, and an average of the 20 measurements taken. The following 

 table gives some of the results : — 



Dr. Edington's Trypanosome. 











In microns. 





Day of 

 disease. 



Method of 

 staining. 







~No. of experiment. 



Average 

 length. 



Maximum Minimum 

 length. length. 



9 



Giemsa 



15 



•3 



20 -0 



13 -0 



30 





13 



•o 



16 -0 



10 -o 



30 





13 



: 



17 -0 



10 -o 



30 



Methyl green ... 



13 





18 -0 



10 -o 



30 





15 



•o 



18 -0 



13 -0 



30 





13 



"5 



17 -0 



11 -o 



22 



G-iemsa 



13 



•o 



16 -0 



9-0 



18 





12 



"5 



16 -0 



8-0 



14 





13 



O 



16 -0 



10 -o 





Average 



13 



•6 



17 -1 



10 4 



134, mouse 

 69, rat 



84, rabbit .. 

 Guinea-pig 

 166, dog .. 



VOL. LXXXI. — B. 



