FLAGELLATED ORGANISMS IN BLOOD OF HEALTHY RATS. Ill 



lowest figure. Occasionally something like granularity may be 

 observed before their disappearance, but not a trace of them is 

 left after their disintegration. It seems as though they had 

 been dissolved in the serum in which they were found. 



Flagellated organisms in the blood of healthy rats. A few red blood-cor- 

 puscles and one white corpuscle are included in the figure. Maguifled 

 700 diameters. 



They may readily be preserved by spreading out a thin layer of 

 the blood containing them over a thin covering-glass and invert- 

 ing it over a weak solution of osmic acid. The preparation 

 should be removed as soon as it presents a dry, glazed appear- 

 ance, and may be thus mounted in the dried condition or in a 

 saturated solution of acetate of potash. I have, however, never 

 been able to detect the flagellum in such a preparation ; appa- 

 rently the refractive index of the substance forming the flagellum 

 and that of the serum approximates so closely that the last can 

 only be detected when creating a current by its movements. 

 The " body " remains nearly as translucent after the action of the 

 osmic acid fumes as it was in the living condition, so that the 

 presence of the protozoa in such a preparation may readily be 

 overlooked, owing to the absence of any movements to direct 

 attention to them. 



When, however, a preparation of blood of this kind is dried in 

 the manner ordinarily suggested for preserving specimens of blood, 

 and especially if a little of a weak solution of aniline blue be after- 

 wards poured over the dried slide, the body of the protozoon 

 will present a very different appearance. It will be found to 

 have contracted irregularly, and to manifest a somewhat granular 

 and shreddy appearance, suggestive of a coagulated, fibro-albu- 

 minous substance. The "body^' portion becomes flattened 

 towards its middle to double its original width, and both ends 

 become almost acutely pointed. The flagellum part is only 

 visible for about half its true length, and this portion of it 

 appears to consist of the same substance as the body. Possibly 

 the now invi'iible portion of the flagellum mav consist of a 



