88 



The Indian Plague Commission came to tlie conclusion that the 

 plague bacilli reached the blood of the host through the faeces 

 of the flea soiling the wound. The author thinks that this may 

 be quite true of Ctenocephalus canis because the faeces of this 

 flea are \eTx liquid and are ejected during the act of sucking 

 blood, but both he and Mr. Often have observed that X. cheopts 

 and P. ahalae, at all events in Java, act very differently; as also 

 Ceratophyllus fasciatus, the faeces of whi'ch are hard and are 

 obviously detached from the body with some difficulty. Occasion- 

 ally the fleas become attached by their faeces and die in conse- 

 quence. Eor these reasons the author thinks that the chance of 

 the wound being infected in this way is not great. 



In an experiment in which infection of the wound by faeces 

 was absolutely excluded, all the guinea-pigs and 4 out of 5 rats 

 became infected and died of plague. A number of investigations 

 were made on the position of the plague bacilli in the gut of the 

 flea, and the midgut was found to contain rather more than the 

 rectum . 



The author next investigated the infectivity of other human 

 parasites, Peclicnliis hominis and Cimex rotundatvs, in 11 

 different cases. Seven out of nine inoculations of guinea-pigs 

 by the former caused plague, but those with C. rotundatvs did 

 not, possibly from want of sufficient material. The smallest 

 number of lice which produced plague was 13, and the author 

 was quite satisfied that P. Jwviinis harbours plague bacilli and is 

 capable of transmitting the disease from man to man. 



Flea Census. — This was carried out over the province of Malang 

 and its districts by Dr. Van Loghem by catching large numbers 

 of field rats and counting the fleas on them. It was found that 

 these carried a much smaller number of fleas than house rats, and 

 it was further discovered that the number of fleas per house rat 

 varies greatly in different districts. In two districts, Ngantang 

 and Pakis, the number rarely exceeded one, whereas in Karaugloo 

 and Senggoeroeg it was more than 3 and often more than 4. By 

 means of a map of the district of Malang shoM'ing the distribu- 

 tion of fleas from January to July 1912 and also the distribution 

 of human or rat plague, it is clearly proved that a large flea 

 census generally coincides with plague, but there are certain 

 exceptions which are very difficult to explain. The investigators 

 think that the increase of the number of fleas per rat shortly 

 before an outbreak of plague might be the consequence and not 

 the cause of rat plague, the latter causing a concentration of the 

 fleas by the death of many rats. This agrees with observations in 

 India. This question of the flea census is discussed at great 

 length and with minute detail. 



The hionomics of X. cheopis. — The author determined that this 

 flea's life-history covered 31 to 52 days. He discovered that 

 excessive moisture, amounting to saturation of the atmosphere, 

 under the given temperature conditions, was fatal to the larvae 

 and he thinks that this may account for the small number of 

 fleas found on field rats living in holes in the rice-fields. 



