LEISHMANIA DONOVANI 419 



In bugs dissected eight to ten days after feeding, tlie flagellate forms had given rise 

 to rounded bodies again. The various stages were compared with the similar 

 natural flagellates of insects, and were described as pre-flagellates, flagellates, and 

 post-flagellates. It was found, however, that the flagellates did not persist in the 

 bug, and, furthermore, it was noted that a second feed of blood often caused the 

 organism to disappear more quickly. The writer (1912c and 19156) criticized the 

 conclusions drawn from these experiments, and pointed out that the development 

 which took place in the bug was probably due to the large quantity of blood in the 

 stomach, and that it represented merely a temporary culture as occurred in the test- 

 tube. This view received support from the fact that a development of Tryiyanosoma 

 lewisi would take place in the bug, which cannot be considered to be a host for this 

 flagellate. Patton was never able to demonstrate actual transmission by bed bugs. 

 Mackie (1914 and 1915) publislied an account of further investigations with the 

 bed bug. He dissected over 1,500 bugs from kala azar areas without finding a 

 single one infected. Two monkeys were inoculated with 209 and 606 crushed bugs 

 without becoming infected. Young bugs born in the laboratory to the number of 

 131 were fed on kala azar cases. In only two dissected twenty four hours after 

 feeding were leishmania seen. On another occasion, 191 young bugs gave a negative 

 result. Cornwall and La Frenais (1916) succeeded in causing bugs to ingest cultural 

 forms of L. donovani. The bugs were then fed on rabbits. It was found that in 

 some cases the flagellates multiplied and persisted up to twenty-nine days. Attem]3ts 

 were made to infect citrated rabbit's blood by causing these bugs to bite through 

 skin. The blood was then distributed in N.N.N, medium. In no case was a culture 

 of flagellates obtained. The faeces of the bugs never contained encysted forms of 

 the flagellate such as are found in the fseces of insects with a natural flagellate 

 infection. Rounded forms and flageUates were, however, seen in the rectum, but 

 these appeared to be in process of degeneration. A peciiliar type of organism, called 

 the " thick-tailed form," was seen in the biigs. This consists of a rounded body of 

 the usual leishmania structure measuring 5 to 6 microns in diameter, and provided 

 with a long flageUum which is very much thicker than that of the ordinary flagel- 

 lated forms. It is thus apparent that the bed-bug hypothesis has not been 

 established, and no proof has yet been given that the development which takes place 

 in the bug is other than a temporary culture of the organism. This is all the more 

 probable from an account of investigations made by Patton, La Frenais, and Rao 

 (1921) in Madras. By feeding bugs on material containing Leptomonas pulicis, 

 Crithidia ctenocephali, and Ilerpeiomonas muscarum, and making cultures in N.N.N. 

 medium from the alimentary tracts of the bugs at varying intervals, it was shown 

 that these flagellates persisted for twenty-four, eight, and forty-five days respectively. 

 By similar experiments made by feeding bugs with cultures of Leishmania tropica and 

 L. donovani, these authors (1921) obtained cultures from bugs after forty-four and 

 forty-one days respectively. Shortt (1923) has also obtained active multiplication 

 of Leptomonas ctenocephali in the intestine of bugs fed on cultures. 



A series of experiments with bugs was conducted by Adie (1921) in India. Many 

 attempts were made to obtain a satisfactory develojunent of L. donovani in the bed 

 bug, but without result. Finally, some bugs which had died after being fed on spleen 

 puncture material from a case of kala azar were placed in saline solution in the 

 incubator at 27^ C. These were examined about thirty-six hours later, and in one 

 tliere were found numerous developmental forms of leishmania. These not only 

 occurred in the lumen of the gut, but also in the intestinal cells in clusters, which are 

 compared with the intracellular stages of development of T. lewisi in the flea. 

 Apparently, similar stages were not found in the numerous live bugs dissected, so 

 that it would seem that here, again, the development was of the cultural type, and 



