256 THE HAEMO I-LAGELLATES 



can and does become intracellular in the Vertebrate host, that a brief 

 consideration of them is essential to the completeness of this article. 



The Leishman- Donovan bodies are constantly found in certain 

 tropical fevers (such as Dum-dum fever, Kala-Azar), particularly pre- 

 valent throughout Indo-Burmah, of which they are now generally admitted 

 to be the cause. These parasites were discovered by Leishmau in 1900, 

 but before his first account of them was published (91) they were also seen 

 independently by Donovan. Moreover, organisms very similar to these 

 parasites (indeed, morphologically, the two kinds are hardly distinguish- 

 able) are found in various sores or ulcers (known as Delhi boil, Oriental 

 sore, " bouton d'Alep "), to which people in different parts of the tropics 

 are liable. The latter were first clearly recognised and described by 

 Wright (97). 



In the former type of disease, there is a general systemic infection, 

 the parasites spreading to all parts of the body, and being met with in 

 the spleen, where they are usually very abundant, liver, bone-marrow, 

 and (more rarely) in the peripheral circulation. The latter type of 

 disease, on the other hand, is one of localised infection, the organisms 

 being restricted to the neighbourhood of the skin lesions ; and in this 

 case the parasites never seem to become distributed throughout the body, 

 producing a systemic infection. For this reason, though the organisms 

 in the two cases seem to be undoubtedly closely related, they are probably 

 specifically distinct. In the Vertebrate host, the parasites are generally 

 intracellular. Free forms are met with, doubtless liberated by the break-up 

 of the host-cells, but these probably soon invade fresh cells. Leish man's 

 form is parasitic in large uninuclear leucocytes (Fig. 39, II), and especially 

 in cells of the vascular endothelium, which are often packed with the 

 little bodies, becoming greatly distended (as macrophages). According to 

 both Donovan (88) and Laveran and Mesnil (90), the parasites also 

 occur in the red blood-corpuscles. Wright's form occurs in the ulcer 

 cells, and in large migratory corpuscles (phagocytes) of the granulation- 

 tissue. 



The parasites themselves are very minute, and usually ovoid or 

 pyriform in shape, the latter being perhaps the more typical. The 

 splenic form is somewhat smaller than the localised type, being 3|-4 p, 

 in length by l|-2 p. in width (39, I), while Wright's form is about 4 fj. 

 by 3 //, (39, III). The cytoplasm is finely granular and fairly uniform 

 in character ; but sometimes it is vacuolated. The most interesting 

 point about the morphology is the fact that two chromatic bodies, of very 

 unequal size, are invariably to be recognised. The larger nuclear body, 

 which corresponds to the trophonucleus of an ordinary Haemoflagellate, 

 is usually round or oval ; the smaller one, representing a kinetonucleus, 

 has the form either of a little rod or of a round grain, and stains very 

 deeply. The two nuclei are generally quite separate, but sometimes they 

 appear to be connected. The organisms multiply in two ways : (a) by 

 binary fission, and (6) by multiple division or segmentation. The chief 

 stages in the first method are well known (Fig. 39, I, 6) ; they offer great 

 resemblance to the corresponding process in Piroplasma. Multiple division 

 has not yet been so satisfactorily made out. It appears to conform more 



