5° 



ZOOLOGY FOR MEDICAL STUDENTS 



CHAP. 



trypanosomes drawing in their flagella and assuming a rounded or spindle 

 shape as a preliminary to dividing. 



Leishmania 



Leishmania. In Assam, Lower Bengal, and occasionally in other 

 parts of India there occurs a somewhat malaria-like fever known as 

 " Kala-azar." In 1900 Leishman discovered the parasitic cause of the 

 disease — in the form of small rounded or oval bodies measuring about 

 4 /i by 3 /i or less, which are to be found embedded in the cytoplasm of 

 the large amoeboid cells of the spleen (Fig. 20, A, L). The true nature 



t K 



B 



Fig. 20. 



Leishmania. A, Large cell from human spleen containing nine parasites ; B, two parasites more 

 highly magnified ; C, D, stages taken from artificial cultures. K, Kinetonucleus ; L, Leishmania ■ 

 M, host cell ; 7i, nucleus of host cell ; t, trophonucleus. 



of these " Leishman-Donovan bodies " is hinted at by the fact that each 

 when stained with a chromatin stain is seen to have within it two deeply 

 stained structures — a larger rounded and a smaller rod-shaped (Fig. 20, 

 B, t and K) — ^which clearly recall the trophonucleus and the kineto- 

 nucleus of a trypanosome, and Rogers was able to show eventually that 

 when inoculated into certain culture media containing blood, especially 

 if slightly acid, these bodies lengthen out, develop a flagellum and swim 

 about as creatures resembling the genus Leptomonas (Fig. 20, D). Nothing 

 definite is known regarding the transmission of the parasite but it has 

 been found to develop into the flagellate form when taken into the 

 alimentary canal of bugs and this suggests that these insects may be the 

 normal intermediate hosts. 



