FLAGELLATES IN PLANTS 59 



herpetomonads. The Herpetomonas from Nepa cinerea 

 the water scorpion is also of great interest, since 

 the parasite, H.jaculum, is gradually evolving heredi- 

 tary infection of the bug. For some time the stable-fly, 

 Stomoxys, has been under suspicion as a carrier of 

 certain diseases common in India and the East, and 

 known under various names. It has recently been 

 shown that the Herpetomonas of these flies is a 

 parasite of the insects, and is not concerned with 

 these maladies. 



The human disease known as Kala-azar, which is 

 very prevalent in Southern India and is spreading in 

 the Sudan, is a remarkable one due to a flagellate, 

 a herpetomonad, which probably spends part of its 

 life in the common bed-bug, and there develops into 

 the flagellate form. By the bite of the bug the flagel- 

 lates are believed to be transferred to the blood of the 

 human victims. There they probably become enclosed 

 in the colourless cells of the blood, lose their flagella, 

 round off, and are known as the Leishman-Donovan 

 bodies. Hence the parasite is called Leishmania 

 donovani. The connexion between the Leishman- 

 Donovan bodies and the flagellate of the bug was 

 worked out also by Captain Patton, who ranks as one 

 of the foremost investigators of the time so far as the 

 flagellates of insects are concerned. 



Another remarkable parasitic flagellate is the one 

 that attacks various species of Euphorbia trees in 

 the tropics. The first flagellate discovered in the 

 Euphorbias was named Leptomonas davidi by its 

 discoverer. The present writers possess specimens 

 of this parasite, and consider that it is a Herpeto- 



