492 FAMILY: TRYPANOSOMIDiE 



all the individuals at the same time and at approximately the same rate, 

 so they all arrive at maturity together. During the development of 

 flagella and the transformation into trypanosomes division may still take 

 place (Fig. 207, 24-28). Rupture of the cell liberates the trypanosomes, 

 which escape into the blood-stream. According to Brumpt (1912), when 

 they first enter the blood-stream they are very narrow, active trypano- 

 somes which grow into the broader forms. A point which does not appear 

 to be definitely decided is whether the infection of fresh cells is brought 

 about by the blood trypanosomes entering new cells, and there becoming 

 again transformed into leishmania forms, which recommence the division 

 process, or whether new cells are infected by leishmania forms escaping 

 from ruptured cells. In sections of the organs of infected mice or guinea- 

 pigs, the writer has often seen ruptured cysts containing the leishmania 

 forms, and isolated leishmania forms scattered amongst the cells, so that it 

 does not seem improbable that they might continue the process of multipli- 

 cation if taken into the cytoplasm of other cells. It might be supposed 

 that the blood type is only capable of development in the invertebrate 

 host, but this does not seem to be the case, for all the phases of reproduction 

 of leishmania forms within the cells will commence after inoculation of an 

 animal with blood containing the mature trypanosomes. 



Chagas (1909) described a peculiar form of pulmonary reproduction 

 in which small cysts are produced by the looping of a trypanosome into a 

 ij-shape and its concentration into an ovoid body. The kinetoplast is 

 supposed to be thrown out, and the nucleus divided into eight small nuclei. 

 Finally, the contents of the cyst divide into eight small merozoites, which 

 are presumed to enter the red blood-corpuscles and develop into mature 

 trypanosomes of the male and female type. This method of reproduction 

 has not been confirmed, and there is little doubt that Chagas was dealing 

 with another organism, probably Pneumocystis carinii (Fig, 450). 



Hartmann (1910, 1917) has described a process of schizogony which 

 commences by a single trypanosome becoming a leishmania form within 

 a cell. Nuclear and kinetoplast divisions take place repeatedly, and by 

 growth a large cytoplasmic body is produced containing many nuclei 

 and kinetoplasts. Segmentation into separate leishmania forms then 

 occurs. Hartmann also describes a schizogony stage in which the nucleus 

 alone is present, the kinetoplast being absent. The figures given by Hart- 

 mann are far from convincing, and suggest the presence in a cell of numerous 

 leishmania forms which have lost their outlines through degeneration. 

 The schizonts appear to be portions of the cytoplasm of cells containing 

 the nuclear remains of degenerating or badly fixed parasites. Similar 

 appearances have led to the view that Leishmania donovani also repro- 

 duces by schizogony (p. 408). 



