22 



MASTIGOPHOEA. 



flagella. These parasites are the cause of Sleeping Sickness 

 in man, of Nagana or Tsetse disease in stock, of Surra in 

 horses, the Mai de caderas and the Dourine of horses. Trypa- 

 nosomes (fig. 4) are specially characterised by possessing an un- 

 dulati]ig membrane. They are more or less spindle-shaped, and 

 along one side runs the undulating membrane. S^ear one end 

 of the cell is found the micronucleus or centrosome. The 

 flagellum arises from this body and runs along the free edge 

 of the membrane to the other end of the cell, and continues 

 on as a free flagellum, but it may end with the termination 

 of the undulating membrane. The true nucleus or macro- 



Fin. 3. — Mastigophora and Foramixifera. 



i. EugUnfi. ii. CercoiaoiHt.-^ intestl.nalis. iii. Po?i//ojna, free and encysted, 

 iv. TcxtiUarid. v. Globigeriiw. (Greatly enlarged.) 



nucleus is placed near the middle of the body. In the genus 

 Trypanoinlasma (Lav. et Mesn.), the centrosome is large, and 

 there are two flagella, one at each end of the body. 



With but few exceptions Tri/j>a»o.<oma and Trypanojylasma 

 are blood parasites, and occur free in the blood plasma, never 

 within blood corpuscles. All the latter are blood parasites, but 

 some of the Tnjpanosomes may be found in lymph and other 

 serous fluids. Large numbers of these protozoa occur in the 

 blood of mammals, birds, reptiles, tish, iV:c., but most are not 



