THE H^MOFLAGELLATES. 257 



to be found, in greater or less number, in the other organs, 

 — liver, kidneys, mesenteric glands, — and in the granulation 

 tissue of intestinal ulcers and skin lesions. 



In films or smears made from " spleen-pulp " many of the 

 parasites seem to be "free " — i. e. not definitely intracellular. 

 They are, however, embedded in a zooglcea-like matrix or 

 stroma, and frequently clustered together in groups. This 

 matrix is composed of rounded or irregular elements, of a 

 finely-granular or reticular nature, and varying greatly in 

 size, which have more or less run together to give the 

 stroma-like appearance. The generally-accepted explanation 

 of this structure (which is not evident in sections of the 

 same material) is that of Christophers, who considers it to 

 be mechanically produced during the preparation of the film 

 by the rupture or fragmentation of the large macrophages. 

 These often possess cytoplasmic buds or outgrowths, easily 

 detachable from the main cell, and each usually containing a 

 larger or smaller number of the parasites. 



There can be no doubt that a similar process goes on 

 normally. The organisms appear to be quite uninjured by 

 the leucocytic cells ; but these, on the contrary, when 

 strongly infected, or after endogenous multiplication has 

 gone on for some time, become vacuolated and gradually 

 used up, and reduced to a mere skin or envelope, which at 

 length ruptures and liberates the enclosed parasites, just as 

 in the case of an ordinary Hsemosporidian. It is not known 

 if the parasites remain free in the general circulation for any 

 length of time before invadiug a fresh host-cell; the life- 

 history has not yet been sufficiently ascertained for us to do 

 more than conjecture. It appears not unlikely, however, 

 that multiplication also goes on in this condition. Certain 

 workers (e. g. Laveran and Mesnil, Donovan, and Rogers) 

 figure multiplication forms free in the blood, and from 

 analogy, either with Piroplasma or a Trypanosome, such 

 an occurrence might be expected. It is most likely that, here 

 also, time and circumstance are largely responsible for the 

 behaviour of the organisms when liberated. 



