LEISHMANIOSIS 491 



blood placed in a refrigerator, whereas the Tr. Brucei soon dies 

 under the same conditions. The two forms do not protect against 

 each other. The Tr. Lewisi is readily cultivated on rabbit-blood 

 agar and is transmitted by the rat-flea, in which it seems to pene- 

 trate into the epithelial cells of the gut and there undergoes a process 

 of multiplication. 1 It is passed in the faeces of the flea and a rat 

 ingesting the infected faeces becomes infected. 



A number of other trypanosomes have been found in the lower 

 animals, birds, fish, reptiles, and amphibians. A large and charac- 

 teristic one is generally present in the blood of the eel. 



The trypanosomes are usually agglutinated when mixed with 

 the serum from an infected animal. 



Hewlett was unable to obtain any toxic or immunising substance 

 from ground-up trypanosomes (Tr. Brucei). 2 



Levaditi and Twort 3 have found that the filtrate of broth cultures 

 of B. subtilis is markedly trypanocidal in vitro but not in vivo. 



Examination of Trypanosomes, etc. 



The trypanosomes, if numerous, are readily observed in the 

 fresh blood. A very shallow cell may be formed on a slide by 

 ringing with melted paraffin. For stained preparations theLeish- 

 man stain (see " Malaria ") or the Heidenhain method (p. 485) 

 may be employed. 4 



Leishmaniosis 



This term is applied to a group of diseases, caused by 

 a similar parasite, and widely distributed in tropical 

 and sub-tropical countries of the old and new world. 5 



In kala-azar or tropical splenomegaly, a disease met 

 with in India, Assam and the East, a small parasite, the 

 Leishman-Donovan body, occurs in large numbers in the 

 spleen and liver, also in the lymphatic glands, lungs, and 

 intestinal submucosa, and in large rnononuclear leucocytes 



1 Minchin and Thompson, Brit. Med. Journ., 1911, vol. ii, p. 361. 



2 Proc. Roy. Soc. Lond., B., vol. Ixxxiv, 1911, p. 56. 



3 Ccmp. Rend. Soc. Biol, vols. Ixx and Ixxi, 1911. 



4 For a special method of staining, see Plimmer, Proc. Roy. $oc.. 

 Lond., B. vol. Ixxix, 1907, p. 102. 



5 See Hewlett, Practitioner, 1911, July, p. 109. 



