102 Effects on Rats of the Trypanosornata of Gambia Fever, etc. 



NOTE ON METHODS. 



With regard to the mention made in Section 4 of methods, the following, which has 

 been used by the writer for some years, gives uniformly good and, as he believes, accurate 

 results. The specimen is never allowed to dry, and there is no shrinkage of the cells, and 

 the finest cytological details can be observed. 



1. Expose a cover-glass to the vapour of 



Osmic acid, 1 per cent 1 c.c. 



Glacial acetic acid 3 — 5 drops 



for 2 minutes. 



(This can be most conveniently effected by using a block-dish covered by a thin glass 

 having a hole in it rather smaller than the cover-glass used.) 



2. Place a drop of fresh blood in one corner of the cover-glass, and expose again to the 

 vapour for 30 seconds. 



3. Spread the film carefully, and expose again for 15 to 30 seconds to the vapour until 

 the surface appears no longer moist. (The film will not be really dry, and can be easily 

 smeared off the glass with the finger : a really dry film will be much lighter in colour, 

 and cannot be rubbed off with the finger.) 



4. Place the cover-glass in absolute alcohol for 10 minutes. 



5. Place the cover-glass in a faintly rose-coloured solution of permanganate of potash 

 for 1 minute. (Two or three drops of a 1-per-cent. solution to 50 c.c. of water.) 



6. Wash in water for 5 minutes. 



7. Stain in a modified Pomanowsky's stain, made by mixing just before use — 



Azur I, 1 per cent 1 c.c. 



Eosin, B.A., 1—1000 2 „ 



Water 8 „ 



for 15 — 30 minutes. 



8. Wash. 



9. Differentiate in orange-tannin, 30 seconds. 



10. Wash well and drain. 



11. Absolute alcohol for a few seconds. 



12. Alcohol — xylol (in proportion of 2 : 3), two or three changes. 



13. Xylol, and mount. 



Instead of 7 — 13, any other method of staining can be used, according to what structures 

 it is desired particularly to show. 



DESCRIPTION OF PLATE. 



Fig. 1. — Section of half of spinal cord of rat which had been paralysed for 2 months 



before death. X 40. Shows meningitis, the exudation around the vessels, and 

 „ a large area of degeneration. 

 Fig. 2. — Longitudinal section of vessel in spinal cord of rat which had been paralysed for 



6 weeks before death, x 220. Shows the cellular exudation around the 



vessel, and on the right an area of degeneration. 

 Fig. 3.— Trypanosornata from a mash of spinal cord of rat, from which cord fig. 1 was 



photographed, x 1000. Stumpy forms, with very short flagella, staining 



badly, with very little differentiation. 

 Fig. 4. — Trypanosornata in blood of rat which was inoculated with the mash of spinal 



cord from which figs. 1 and 3 were photographed. Long, well- differentiated, 



easily staining forms. This rat was not paralysed. 



