PROTOZOA FOUND IN BLOOD. 



229 



FIG. 77. 



PROTOZOA FOUND IN BLOOD. 



Among the protozoa occasionally found in the blood are the 

 following : 



Filaria Sanguinis Hominis. 



Morphology. The filaria when fully grown are slender and 

 hair-like, measuring 3-6 inches long. They live in the lymphat- 

 ics and tissues exclusively, and dis- 

 charge from there their embryos, 

 which circulate then in the blood. 

 An embryo measures about forty 

 times the diameter of a red blood- 

 corpuscle in length and equals its 

 diameter in width. The embryo of 

 F. bancrofti (Fig. 77) (F. nocturna) 

 is found free in peripheral blood 

 only at night, that of the F. diurna 

 only in the daytime, while that of 

 F. perstans is found with equal fre- 

 quency during the night and day. 



Pathogenesis. Chyluria, lymph- 

 scrotum, and elephantiasis are 

 caused by the F. bancrofti and the 

 latter sometimes by F. diurna. Craw- 

 craw, a parasitic disease, is caused 

 by F. perstans. Infection is sup- 

 posed to be carried in water in 

 which are deposited the ova by 

 mosquitoes, in which they develop. An. 



Trypanosomes. 



Trypanosomiasis. Many diseases 

 in man and animals are due to inva- 

 sion by trypanosomes. Several vari- 

 eties of these have been discovered and described. In general 

 they are characterized by a flagellum and undulating mem- 

 brane, a centrosome, nucleus, and nucleolus. The species of 



Ex. 



Nerv. 



Larva of Filaria bancrofti in 

 the blood ofn.au, in Egypt : Nerv,, 

 nervous system; ex., excretory; 

 //., anus. X 514. (Looss.) 



