602 APPENDICES. 



but the author has not been able to persuade himself that they 

 " attack and disintegrate" the red blood -corpuscles. 



In the active state the thicker portion, or body, appears to 

 twist and bend from side to side with great activity. The organism 

 can turn completely round with lightning rapidity, so that the 

 flagellum, at one moment lashing in one direction, is suddenly 

 observed working in the opposite direction. Then suddenly tne 

 organism makes progression, and it can be distinctly seen to move 

 in the direction of the flagellum, the flagellum threading its way 

 betiveen the corpuscles and drawing the rest of the orgcmism after 

 it. Currents set up by evaporation may undoubtedly here arid 

 there produce the appearance of the organism " wriggling along " 

 with its flagellum posterior ; but the author was convinced, after 



FIG. 241. MONADS IN RAT'S BLOOD, x 1200. a, A monad threading its way among 

 the blood-corpuscles ; b, another with pendulum movement attached to a cor- 

 puscle ; c, angular forms ; d, encysted forms ; e and /, the same seen edgeways. 



hours of patient observation, that in the normal mode of progression 

 the flagellum acts as a tractellum and not as a pulsellum. By 

 treating cover-glass preparations with osmic acid the appearances 

 obtained are very similar to those shown in Lewis's photographs, 

 so that there is no doubt, in spite of the descriptions not completely 

 according, that they are one and the same organism. There was a 

 great likeness to the organisms described by Mitrophanow, and to the 

 Surra parasite ; and when the author had stained the rat parasites, 

 the closest examination confirmed his belief that they were morpho- 

 logically identical with the stained parasites of Surra. 



Cover-glasses with a thin layer of blood may be passed three 

 times through the flame of a Bunsen burner in the way commonly 

 employed for examining micro-organisms, and stained with an 



