66 THE PROTOZOA AS PARASITES OF MAN 



nothing to do with either nucleus or movement. Trypanosoma 

 has no mouth, but nourishes itself, like Monocystis, by absorbmg 

 through the surface of its body substances obtamed from the 



juices of its host. . x v,- v, •+ 



In spite of the immense amount of investigation of which its 

 medical importance has caused it to be the subject, the life- 

 histor>' of Trypanosoma is not yet thoroughly understood. In 

 the case of T. gambiense, the cause of the terrible sleeping sick- 

 ness of West and Central Africa, the following facts have been 

 established. In the body of an infected man the parasites live at 



t'.JVUi 



Fig. 38. — Trypanosoma gambiense. 



A, B,C, Slender, intermediate, and stumpy forms from man ; D, ' latent body ' ; E, slender form from gTit 

 of fly ; F, crithidial form from salivarj' gland of fly ; G, ripe form from proboscis of fly. 



bpt., blepharoplast ; ft., flagellum ; k.nu., parabasal body (kinetonucleus) ; tr.nu., trophonucleus ; 

 u.m., undulating membranes. 



first in the blood, but presently make their way into the lymphatic 

 glands, and thence into the fluid of the spinal canal and cavities 

 of the brain. While they are in the blood alone the man suffers 

 from ' Gambia fever ', but when they reach the central nervous 

 system the drowsiness which is characteristic of sleeping sickness 

 comes on, and increases, and is followed by a wasting of the body, 

 till death almost inevitably results. The individuals found in the 

 human host are not all alike, some being long and slender, some 

 short and stumpy, and some intermediate in shape. The thin 

 forms are the youngest, the animals growing stouter as they 

 mature, and becoming stumpy in succeeding generations. There 

 are also differences in size, due to age and to the fact that the 



