274 Mr. H. G. Plimmer and Prof. J. Eose Bradford. 



" A Preliminary Note on the Morphology and Distribution of the 

 Organism found in the Tsetse Fly Disease." By H. G. 

 Plimmer and J. Eose Bradford, F.E.S., Professor Super- 

 intendent of the Brown Institution. Eeceived June 12, — 

 Eead June 15, 1899. 



(From the Laboratory of the Brown Institution.) 



These observations are the result of an inquiry entrusted to us by 

 the Tsetse Fly Committee of the Eoyal Society, at a meeting of the 

 Committee on March 16, 1899. 



The material for our investigations was obtained in the first place 

 from a dog and a rat, inoculated with the blood of a dog suffering 

 from the disease, by Mr. H. E. Durham, at Cambridge. 



The organism found in the Tsetse Fly disease was discovered by 

 Major Bruce, E.A.M.C., F.E.S., and was classed by him as a Trypano- 

 soma. These belong to the order Flagellata, and, according to 

 Butschli, to the sub-group Monadina. 



We will, in the first place, describe the adult form of the organism, 

 such as is met with most frequently in the blood of a susceptible animal 

 affected with the disease. 



A. Description of the Adult Form of the Trypanosoma. 



In freshly drawn blood examined as a hanging drop, or as a very 

 thin layer in a cell, the adult form of the Trypanosoma can be easily 

 studied. The latter method is the better, as the organism can be 

 better seen and more accurately examined, in the thin, uniform layer 

 of fluid than in the rounded drop. The easiest method of examining 

 the blood in this way is to make, with a red-hot platinum loop and a 

 small piece of paraffin, a thin ring of paraffin on an ordinary glass 

 slide ; the drop of blood is placed in the centre of the ring and a 

 cover-glass placed on it, the thin layer of paraffin preventing pressure. 

 If it be desired to keep the blood for continuous examination, it should 

 be drawn into a graduated Pasteur pipette, and one-tenth part of a 

 5 per cent, solution of sodium citrate should be drawn up after it, 

 then the blood and citrate solution should be carefully mixed in the 

 bulb ; the tube should then be sealed up, and drops can be taken from 

 it as desired. 



Under ordinary conditions of illumination the Trypanosoma, as seen 

 in the blood, appears to consist of a uniform, homogeneous mass of 

 protoplasm, of worm-like form, with at one end a thick, stiff extremity, 

 and at the other a long, wavy flagellum. It is generally in active 

 motion, and this is seen to be caused by the rapid lashing movement 

 of the flagellum, and by the rapid contractions and relaxations of the 



