264 THE PROTOZOA 



T. pertenue has been cultivated in the same way as T. pallidum and Nichols 

 infected rabbits by intratesticular injection. A disease of Guam known as gangosa 

 is possibly connected with a tertiary form of yaws. In persons who have had yaws 

 a positive Wassermann reaction seems to be given in a higher percentage than is 

 true for syphilis. Salvarsan is also more specific for yaws than for syphilis. 



TRYPANOSOMES OF SLEEPING SICKNESS 



The African trypanosomiases follow infection with two species of 

 trypanosomes; the more virulent type of the disease, occurring in 

 South Central Africa, being due to Trypanosoma rhodesiense, trans- 

 mitted by Glossina morsitans and that of less severe type, but of 

 more general distribution, being due to T. gambiense and transmitted 

 by Glossina palpalis. The very important Trypanosoma brucei, which 

 is the devastating agent in the African horse, dog and cattle disease, 

 nagana, is also transmitted by Glossina morsitans and there exists 

 the opinion that this trypanosome is identical with T. rhodesiense. 



These trypanosomes are blood flagellates and are typical of the Binucleata in 

 possessing two chromatin staining areas, the larger and more centrally situated 

 mass being the tropho or macronucleus and the smaller, but more deeply staining one, 

 the kineto or micronucleus (Blepharoplast). Trypanosomes have a fusiform or 

 fish-shaped body which stains blue. Near the less pointed, nonflagellated end, 

 usually called the posterior end, is the deeply stained blepharoplast. Behind this 

 is a vacuole and, taking origin from this part of the trypanosome, is the flagellum. 

 This borders an undulating membrane attached to the body and then, carried along 

 to the other extremity, projects free as a long, whip-like flagellum. 



In fresh preparations the body of the trypanosome progresses in the direction of 

 its flagellated end, although occasionally it will be observed to move in the opposite 

 direction. 



T. gambiense varies much in length and breadth. The normal type, as found in 

 the blood, varies from 14 to 20 microns, while longer forms, 20 to 24 microns, are 

 growth ones and, in the longest ones (23 to 33 microns), we have those preparing 

 to divide longitudinally. The normal short forms are the ones from which the 

 development takes place in the tsetse fly. In width these flagellates are from 1.5 to 

 2 microns. The blepharoplast is oval and the nucleus situated about the center. 



With T. rhodesiense the nucleus is typically located almost adjacent 

 to the blepharoplast. As a matter of fact it may require the passage of 

 this trypanosome through rats to bring out these "posterior nuclear 

 forms," the nuclear location being at times almost entirely that of 

 T. gambiense. In addition to the characteristics of nucleus being near 

 the blepharoplast, this trypanosome is more virulent for laboratory 

 animals than T. gambiense, agreeing in this respect with the more severe 

 clinical course in man. 



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