202 SOME MINUTE ANIMAL PARASITES 



to man, and from man to man, the human flea, Pulex 

 irritam, being suspected of having a share in the 

 latter work also. Basile succeeded in infecting 

 young clean dogs by putting them in kennels with 

 infected ones, and considered that the fleas passed 

 from the infected to the healthy animals. The 

 proof that the dog flea is the natural infective agent 

 was not really afforded by Basile's work, for instead 

 of feeding fleas on a heavily infected dog, he fed 

 them on infected spleen pulp, to which, of course, 

 they could not have access in Nature. With regard 

 to the connexion of the dog flea and man, dog fleas 

 were obtained from beds, mattresses, and pillows of 

 infected persons, and as a result of examining 1,000 

 fleas thus obtained from Bordonaro, four were found 

 to contain flagellates. Here, again, an element of 

 doubt was introduced, for the characteristic form of 

 the leucocyte containing the unchanged parasite is 

 not mentioned, and the cycle of changes undergone 

 by the parasite in the flea was not fully detailed. 

 The fact that Herpetomonads, which are true 

 parasites of the dog flea itself, and have no connexion 

 with the dog, are known, renders the paucity of 

 infection of these fleas with flagellates somewhat 

 suspicious. It suggests a natural flagellate of the 

 flea, rather than a developmental stage of the 

 parasite of the dog or of man. 



The coincidence of infantile and canine Kala-azar 

 may have some important connexion, or it may be 

 accidental. While it seems likely that the flea does 

 convey the malady from dog to dog, the case for 

 transference from dog to man is less complete, and 



