89 



A number of experiments Avere made to determine liow far 

 fleas might travel from an animal, and it was concluded that 

 -.Y. chcopis does not travel far, 5 metres being- regarded as a 

 maximum. Amongst the enemies of fleas, ants were found to be 

 very active and the author lost whole broods of larvae from this 

 cause. He also found that large numbers of fleas are attacked 

 by minute mites which he describes and figures. He says that 

 the mite appears to represent the immature stage of some Tyro- 

 glyphid and closely resembles the genus Anoetus, Uuj. These 

 mites caused serious mortality amongst the author's bred fleas and 

 were discovered to have arisen in the bran used to cover the 

 bottoms of the glass jars. In experiments made at another place 

 Avhere sand was used, mites were not found on the fleas. 



Experiments with fumigants for the destruction of fleas led 

 the author to the conclusion that the killing of rats and fleas may 

 be best effected by the use of sulphur dioxide and small articles 

 may be best disinfected by carbon bisulphide. 



Bionomics of the rats. — Elaborate observations were carried 

 out to determine the distribution of the three species of rats. 

 The small rat (Mus concolor) was found to be particularly trouble- 

 some in the houses, from its ability to enter relatively small 

 holes in the bamboo used in their construction. Further observa- 

 tions were made in order to determine the distance to which 

 M. rattus would travel and it was satisfactorily shown that house 

 rats may be found as much as 650 yards away from the nearest 

 village, even where there is no path of any kind. The author 

 is satisfied that the travelling habits of this rat are much greater 

 than is generally supposed, and this has an important bearing 

 upon the spread of plague. The prevalence of trypanosome- 

 carrying house rats and field rats in the province of Malang was 

 investigated and found to be at a maximum of 37 per cent, m 

 March, to diminish to 22 per cent, in -July, and to increase again 

 to 36 per cent, in November; the presence of trypanosomes is 

 regarded as evidence of the transmission of infection from rat 

 to^rat by fleas, and this was found to be less among field rats 

 than house rats. Similarly the distribution of Mus decumanus 

 was carefully investigated, and it w^as found to be confined to 

 isolated colonies. The percentage of trypanosome-carriers m this 

 species was small, alwavs smaller than that of the house rat, but 

 crreater than that of the'field rat, and the author is of opinion that 

 Mus decumanus in Eastern Java does not play such an important 

 part in the epidemiology of plague as in British India . 



Spread of Plague.— It has been shown by the author that 

 lice from plague-infected houses are sometimes infective, but 

 this is of little importance, because infected lice cannot cause 

 rat plao-ue and but 'few cases of human plague. It remained to 

 be inve'stigated to what extent rat fleas were found on natives 

 in Java. From February 1912 the clothes and baggage of 

 travellers leaving the province of Malang were disinfected with 

 carbon bisulphide, the dead parasites being collected on a white 

 sheet and subsequentlv identified. Between 14th February and 

 15th May 1912, 56,790 persons were examined and on them were 



