1906.] of Gambia Fever and of Sleeping Sickness. 99 



ascending the spinal cord from the lumbar region. The lesions in the spinal 

 cord were also confined more or less to the lumbar region, depending for 

 their extent upon the duration of the disease. In two cases I inoculated the 

 animals on the inner side of the foreleg, and both these animals became 

 paralysed in the front legs, and the degenerative lesions were most marked in 

 the corresponding parts of the spinal cord. 



I inoculated two rats in the peritoneum, but in neither did any paralysis 

 occur. 



4. The morphological characters of these two strains of Trypanosomata. 



It is impossible at present to insist that any differentiation based solely 

 upon microscopical observations should be sufficient in the case of organisms 

 so much alike as the trypanosomata. Our methods and observations are 

 neither uniform nor good enough to enable us to make, at the present time 

 by the microscopical method alone, a sufficient differentiation. Until all 

 observers use the finer zoological methods of fixation, etc.,* instead of the 

 barbarous method of drying blood films at present almost exclusively in use, 

 we cannot look for much certainty in the microscopical differentiation of very 

 similar organisms. This must be supplemented by observing the differences 

 in their pathogenic action. 



We must not forget, either, the variability of organisms in the same 

 species of animals in the same country, and their still greater variability in 

 different animals in the same, and in other countries ; and we must remember 

 the great differences in the physical conditions of an organism which are 

 due to environment. So I would not insist, with our present knowledge, too 

 strongly upon the differences in form in the trypanosomata mentioned 

 above, under the different conditions which have been described. But if 

 preparations are made under the same conditions, and with the same care, 

 it can be seen that the trypanosomata from the cases in which paralysis has 

 occurred (in which very few are found in the blood, the greater number 

 being in the central nervous system) are short and thick, with Ijhe flagellum 

 extending very little beyond the body of the organism; they contain a 

 varying number of vacuoles, and sometimes many granules ; they move 

 slowly, even when the smear of cord or brain is diluted with normal citrate 

 solution (fig. 3). On the other hand, those found in the generalised cases (the 

 Gambia Fever type) are long, with a long flagellum, and are not vacuolated, 

 and move quickly (fig. 4). I have not found the other form in any of these 

 cases, even when the animal has been long dying. This short, badly staining, 

 vacuolated form is probably due to some condition of environment about 



* See Note on methods. 

 VOL. LXXIX. — B. I 



