79 



Biological Laboratory, Bureau of Government Laboratories, Manila, 

 P. I. 



Pulex philippinensis appears to be a stationar}' parasite of the 

 rat; it is found in Manila. It is much like P. anomalus recently 

 described by Baker and found by him in California. However, 

 the head, eyes, antennae, palpi, and bristles offer marked points of 

 differentiation. 



It is of interest to mention that Baker in his monograph on 

 American Siphonaptera describes a new species of rat flea from 

 Brazil, South America. It is a very large one, the male being 

 3.5 millimters and the female 5.5 millimeters in length. Evidently 

 there are several different species of rat fleas in different parts of 

 the world. 



EXPERIMENTS WITH FLIES. 



Experiments which have been made to demonstrate that plague 

 may be spread by flies are all inconclusive, because the arrange- 

 ments were such that the transmission of the disease was inevitable. 

 Flies were fed with bouillion containing plague bacilli and after 

 varying intervals of time had elapsed were groimd up. The 

 emulsion so obtained was subsequently injected into guinea pigs 

 or rats, which of course died of the disease. Such experiments 

 can not determine with certainty whether plague can or can not be 

 carried by flies. 



Experiments were therefore conduct which were designed more 

 closely to imitate what might take place in nature. The organs 

 of plague cases, both from man and from guinea pigs, were kept 

 in an anatomical jar, over which was placed a flytrap containing 

 a number of flies. The door of the trap was then opened and 

 the files allowed to come in contact with the plague organs in the 

 lower vessel. After the}' had remained in the lower vessel for 

 varying periods of time (from one to several hours) they were 

 again induced to enter the trap by surrounding the lower vessel 

 with some dark material, which caused them to seek the upper 

 light space. The trap was then closed and placed over an especially 

 constructed fly-proof cage, in which were two guinea pigs. The 

 door of the trap was opened so that the flies could enter the cage. 

 The guinea pigs had been shaved over an extensive area of the back 

 and some sirup had been dropped on a few spots, to attract the 

 flies and to cause them to come in contact with the bodies of the 



