54 REPORT ON DOURINE. 



rat (m. d.). The differences between the trypanosoma of Dourine 

 and that of the rat are most marked. In the latter, the posterior 

 extremity is extremely long and slender, and tapers gradually from 

 before backwards, the micro-nucleus being situated at about the 

 junction of the anterior 4-5th with the posterior l-5th. In Dourine, 

 on the other hand, the posterior extremity is short and sometimes 

 pointed, but more often it is somewhat rounded and the micro- 

 nucleus is placed within a very short distance of the posterior end 

 of the body. When undergoing division, the Dourine trypanosoma 

 may attain even larger proportions than are usually found in the 

 Surra trypanosoma. A marked feature of the Surra protozoon is the 

 presence of large numbers of highly refractile granules in the 

 fresh state and of chromatin grains in stained specimens which 

 occupy positions anterior and posterior to the macro-nucleus spe- 

 cially if the hsematozoon is present in large numbers during each 

 paroxysm and shortly before death. In the case of Dourine these 

 granules are not present to the same extent and are smaller in size ; 

 further, the undulating membrane is less developed than in the 

 former disease and only one mode of division, namely, the longitudi- 

 nal, is observed in mature trypanosomata. The process of division may 

 commence at either end or in the centre of the organism. As a rule 

 either the micro-nucleus first becomes elongated and dumbbell 

 shaped and then divides into two parts, or the chromatin body 

 elongates and divides into two. Sometimes a separation is 

 observed first in the flagellum. Finally, division may primarily 

 effect only the anterior and posterior portions of the organism, and 

 these may become free, while the macro-nucleus for the time remain 

 single. The organism is then only fixed by the middle, owing to 

 the late division of the chromatin body. In stained specimens of 

 trypanosomata in conjugation, the micro-nucleus was observed to 

 have divided into two in each parasite respectively and in one or- 

 ganism, the anterior of the two micro-nuclei attained a size twice or 

 three times the size of the posterior one, although those present in 

 the second trypanosoma remained small. In 1891, in order, if 

 possible, to determine the effect of conjugation between trypano- 

 somata, a small quantity of methylene-blue solution was injected 

 into an aural vein of one rabbit suffering -from Surra, while a small 



