Transmission to Lower Animals 515 



somes, which seem to have much the same specific gravity of the 

 leukocytes, appear in greatest numbers where the leukocytes collect. 

 In African natives the trypanosomes may be present in the blood 

 for a long time before any symptoms are discovered, but in Europeans 

 their presence is soon followed by fever. As the infection progresses, 

 the micro-organisms increase in great numbers in the organs, and 

 almost entirely disappear from the blood. The lymph nodes swell 

 and Winterbottom, who first described the disease, called particular 

 attention to the enlargement of those of the posterior cervical 

 triangle, which he regarded as of diagnostic significance. 



When the blood examination fails to reveal trypanosomes, they 

 may frequently be found by puncturing an enlarged lymph node 

 with a dry needle and examining the drop of fluid obtained. 



Wolbach and Binger* found that the tr3^anosomes invade the 

 connective-tissue structure of all organs, the reticular tissue of lymph 

 nodes and spleen, and the substance of the brain. The lesions are 

 due to the presence of the flagellated form of the parasite in the 

 tissues. They found the initial cell reaction to be the proliferation 

 of endothelial cells. They believe the discovery of numerous 

 intravascular mitoses of endothelial cells in the lung, liver, spleen 

 and kidney to indicate the source of the increase of the large mono- 

 nuclear leukocytes of the blood in human trypanosomiasis. 



Lymphocytosis is the rule in trypanosomiasis but is of no diag- 

 nostic importance. 



As the invasion of the body continues, the trypanosomes dis- 

 appear in large measure from the. blood to multiply in the organs. 

 In the spleen, in particular, the parasites assume a different form: 

 a deep band makes its appearance between the nucleus and the 

 blepharoplast. The former becomes surrounded by a large vacuole, 

 and the trjrpanosome becomes disintegrated and reduced to a 

 nucleus, which represents the latent form of the organism. The 

 nucleus later divides giving rise to a new blepharoplast from which a 

 new flagellum arises, an xmdulating membrane later forms, and the 

 usual appearance of a trypanosome again develops. When perfected, 

 this new trypanosome enters the circulating blood. At the time that 

 the first indications of somnolence appear, the parasites are present 

 m the cerebro-spinal fluid. The fluid is collected by the technic 

 given in the chapter upon cerebro-spinal meningitis. To find the 

 trypanosomes in the fluid, it should be rapidly centrifugalized for a 

 few mmutes and the whitish sediment collected, and examined imme- 

 diately, when the micro-organisms may be studied alive, or the fluid 

 may be spread upon slides and stained according to the technic 

 for blood spreads, when, the trypanosomes being killed, fixed and 

 stained, their structure can be studied to advantage. In studying 

 the morbid anatomy of sleeping sickness, Mottf came to the con- 



* "Jour. Med. Research," 1912-1913, xxvn, 83. 

 t "British Medical Journal," Dec. i6, 1899, n. 



