490 FAMILY: TRYPANOSOMID^ 



(1912) believes tliat the narrow forms are the young ones escaped from the 

 cysts, and that they gradually grow into the broader individuals. The 

 nucleus is central in position, while the kinetoplast is a relatively large 

 ovoid or egg-shaped body close to the pointed posterior end. The undulat- 

 ing membrane is narrow and only slightly convoluted. The flagellum 

 represents about a third of the total length of the organism. The curved 

 character of the short broad body with the large "egg-shaped" kineto- 

 plast and comparatively straight membrane gives T. cruzi at this stage 

 of its development a very characteristic appearance. Chagas described 

 certain forms within the red blood-corpuscles, but this observation has 

 not been confirmed, and it is probable he was merely dealing with super- 

 imposed trypanosomes or other structures. T. cruzi appears to be a 

 peculiarly fragile organism, for in the process of making blood-films from 

 infected animals many of the trypanosomes are damaged. 



Escomel (1919a) described what he believed to be the first case of 

 T. cruzi infection to be noted in Peru. In his description of the trypano- 

 some he gave the length as 20 to 40 microns, and stated that the kinetoplast 

 was not well developed. From the description, it appeared to Yorke 

 (1920a) that Escomel must have been dealing with some trypanosome 

 other than T. cruzi. He accordingly proposed to name it T. escomeli. 

 In the following year Escomel (1920) gave a more detailed account of the 

 trypanosome. He corrected his previous measurements, while from the 

 figures he gave there is little doubt that he was actually dealing with 

 T. cruzi, so that the name T. escomeli becomes a synonym. 



Multiplication. — Longitudinally dividing forms of T. cruzi, such as 

 are found in the blood in the case of other trypanosome infections, do 

 not occur, and this is explained by the type of reproduction which was 

 specially studied by Vianna (1911), and which bears a striking resemblance 

 to the method of multiplication of the trypanosome of the bat, Vesperugo 

 pipistrellus, as described by Chatton and Courrier (see p. 480). The 

 multiplication of T. cruzi takes place within the cells of nearly every 

 organ of the body — not only the endothelial cells of the capillaries and 

 lymphatics, but also the organ cells themselves. In some cases one 

 organ is more involved than another, a feature which accounts for the 

 special symptoms seen in certain cases. The heart and voluntary 

 muscles, the nervous system, thyroid, lymphatic glands, bone marrow, 

 suprarenal capsules, ovaries, and testis have all been found invaded by 

 the multiplying forms. The process can be readily studied in sections of 

 the heart muscle and other organs of mice, rats, and guinea-pigs, or in 

 smears made from these organs (Fig. 207). Multiplication appears to 

 commence after the invasion of a cell by a single trypanosome which, 

 losing its membrane and flagellum, becomes a leishmania form measuring 



