394 FAMILY: TRYPANOSOMID.E 



wise, is described as becoming infected after being made to ingest lleas, some of wliich 

 harboured L. ctenocephali. A more extensive series of experiments was published 

 later (1915&). In these, four flagellates were used [L. jaculum, L. stratiomyice, 

 L. pedicuU, and C. gerridis), and various vertebrates as follows: the stickleback 

 (Gasterosieus aciileatus), newt {3Iolge vulgaris), frog (Bana temporaria), toad {Bufo 

 vulgaris), lizard {Lacerta vivipara), snake {Tropidonotus natrix), and mice {Mus 

 musculus). These animals were infected with one or more of the flagellates, either 

 by inoculation or feeding. In many cases, Fantham and Porter believe that the 

 organisms acted as pathogenic agents, and brought about the death of the animals. 

 Still another series of experiments is recorded by these observers (1915c). On this 

 occasion, they claim to have infected birds (canaries, martins, sparrows) by feeding 

 them with L. jaculum or L. culicis of Cnlex pipiens. In these experiments they 

 claim to have found leishmania and flagellate forms of the parasites in the blood 

 and various organs, and state that the birds became ill from the infections induced. 

 It is suggested that it is possible that in nature these infections may be one of the 

 causes of mortality amongst birds. 



The remarkable feature of all these experiments is the apparent ease with which 

 infections were produced. Other workers, as, for instance, Noller (1912(Z), failed 

 to infect a young dog with L. ctenocepliali. Chatton (1919) failed entirely to infect 

 mice with the same flagellate, and the writer has had a similar experience with the 

 cultures of the leptomonas of Pulex irritans. Tyzzer and Walker (1919) conducted 

 very careful experiments with L. ctenocephali. Though they inoculated mice, some of 

 which were newly-born, by various routes, they never succeeded in producing an 

 infection. Patton (1921) has stated that he has failed entirely to infect mice with 

 several species of insect flagellate, while Glaser (1922) attempted without success 

 to repeat Franchini and Mantovani's experiments with H. muscarum. Hoare 

 (1921rt) made a very careful study of the question, and carried out a series of experi- 

 ments with the flagellates of GalUphora sp., ISlepa cinerea, and Meloplmgus ovinus, 

 The vertebrates inoculated or fed with one or other of these flagellates were mice, 

 newts, frogs, and sticklebacks. Though very searching observations were made, 

 involving not only the examination of smears, but also cultures from the heart blood 

 and organs, in no single instance was an infection demonstrated. Hoare' s experi- 

 ments indicate, at any rate, that infections cannot easily be produced, and that the 

 claim that purely insect flagellates may take on pathogenic properties seems very 

 doubtful indeed. As Hoare points out, in conducting experiments of this kind, only 

 undoubted leishmania forms should be accepted as evidence of infection. In the 

 successful experiments recorded above, the observers have undoubtedly been willing 

 to accept as leishmania forms bodies of a doubtful nature. This is clearly shown by 

 the frequent references to leishmania forms with a single nucleus and the anaplasma 

 forms in cultures. Roubaud and Franchini (1922), for instance, state that the 

 parasites in the infected mice mostly had a single nucleus, and that the kinetoplast 

 . was very difficult to distinguish. In the absence of a kinetoplast, it is not easy to 

 comprehend the reasons for regarding the bodies as flagellates at all. They might 

 equally well be yeasts, the organism which has been named Encephalitozoon, or the 

 merozoites of some Sporozoon such as Klosiella, which may infect the endothelial 

 cells of the bloodvessels. 



Glaser (1922) made unsuccessful attempts to infect six mice, a rat, and a guinea- 

 pig with //. muscarum, while Shortt (1923rt) conducted a series of experiments 

 with L. ctenocephali of the dog flea, and L. lucilice of Lucilia craggii, and rats, mice, 

 monkeys, dogs, pigeons, and frogs. The animals were either fed or inoculated 

 in various ways, and were subsequently examined by the smear and culture 

 method. Over fifty experiments were made, and in not a single instance was 



