120 INFECTIOUS DISEASES DUE TO PROTOZOA 



for sonic time. Besides the pyriform parasites a considerable 



number of single forms somewhat irregular in outline may be 

 found. These forms undergo ameboid movement. 



Alkaline methylene blue stains the parasites a blue color leaving 

 the red corpuscles unstained. Methyl violet gives much the same 

 result. The parasites are stained by carbol fuchsin; but this stain 

 also stains the corpuscles deeply. Much better results are obtained 

 by using the Romanowsky method of staining or one of its modi- 

 fications. Chromatin bodies within the parasites are brought out 

 by the use of one of these stains. With the Romanowsky method 

 of staining the smallest forms appear as very small rings about 

 one-eighth the diameter of a corpuscle. The periphery of the 

 ring takes a red color in a greater or less extent, while the re- 

 mainder appears blue. Other very small parasites have a very 

 irregular outline and contain two, sometimes four, chromatin 

 bodies of a red color. In the large double pyriform parasites a 

 red chromatin body is found usually at the broader pole, some- 

 times in the middle (Kossel). Ziemann observed forms with the 

 chromatin bodies at the pointed end. The remainder of the body 

 of the parasite stains blue. The chromatin body is ordinarily 

 rounded. 



The number of infected corpuscles is usually about one-half 

 to one per cent, of the entire number of red corpuscles. Some- 

 times a long search is necessary to find a parasite. When the 

 number becomes larger, death may be expected within 24 hours. 

 Toward the fatal termination five to 10% infected corpuscles 

 may be found. Very rarely large numbers of parasites may be 

 present and yet the animal recover. Smith and Kilbourne ob- 

 served one such case (No. 49), in which hemoglobinuria was 

 present. Parasites are present in the internal organs in much 

 larger numbers than in the peripheral circulation. The distribu- 

 tion of the parasites is well shown in one of Smith and Kilbourne's 

 cases, No. 163. This cow was killed when the temperature was 

 107° F., red corpuscles 2,645,000 per cram. Four days before 

 the temperature was normal, the red corpuscles numbered 5,000,000 

 per cmm. Before she was killed there were two to three per cent, 

 infected corpuscles in the peripheral blood. Examination of the 

 internal organs showed 50% in heart muscle and hyperemic fringes 

 of the omentum, 10-20% in liver and in kidney, five per cent, in 



