290 Dr. L. Rogers. Development of Hepatomonas of [Oct. 16, 



twentieth to one-sixtieth, thus readily accounting for the frequency of 

 terminal infection by such diseases as dysentery, cancrum oris, pneumonia 

 and phthisis, owing to loss of phagocytic power, while I have also found 

 the opsonic index reduced against the staphylococcus pyogenes aureus, which 

 is frequently present in the spleen in cases of cancrum oris. 



The Bearing of the Flagellation of the Parasite in Sterile Acid Medium on 

 the Probable Mode of Infection. 



The two factors which I have found most essential to a uniform develop- 

 ment and very rapid multiplication of the flagellated forms are sterility and 

 a slightly acid, or, at least, a neutral medium. I have also tried blood agar 

 after Novy's method, only using human blood in its preparation, but failed 

 to obtain either sub-cultures of already developed flagellates or of the spleen 

 parasites, while only very scanty development was obtained when several 

 drops of spleen blood, with very numerous parasites, were added to a 

 previously acidified blood agar tube, and then only in the added blood as 

 by the ordinary method. Now the only condition under which the 

 Leishman-Donovan bodies would be likely to meet with a sterile acid medium 

 on their escape from the human body would be in the stomach of some 

 blood-sucking insect, of which the common bed bug, or possibly mosquitos, 

 are the most likely hosts, for clinical reasons I have elsewhere pointed out, 

 while I have found that after sucking blood it becomes acidified in gastro- 

 ntestinal tract of bugs, and is also frequently sterile. I have not yet 

 succeeded in inducing these insects to suck infected spleen blood placed in 

 capsules of various kinds, but, on the other hand, I have mixed the contents 

 of their stomachs after feeding on human blood (which was proved to be 

 free from anything resembling any stage of the Hepatomonas of kala-azar) 

 with about an equal quantity of spleen blood containing the parasites, and, 

 after incubating in capillary tubes at 22° C, have been able to watch the 

 development of the parasites day by day up to the flagellated stage under 

 these conditions in those which remained sterile, but not when any bacteria 

 were present. It is therefore clear that the conditions met with in the 

 stomachs of bugs — and possibly also of mosquitos — are not inimical to the 

 development of the parasite into the flagellated stage, provided the 

 temperature conditions are suitable. 



The more difficult question whether opportunities for infection of such 

 insects occur sufficiently frequently to account for the incidence of the disease 

 remains to be considered. In the first place, it is conceivable that bugs 

 especially might become infected from skin lesions containing the parasites, 

 for these may occur on parts of the body little exposed to the bites of 



