90 



to say, only 3 rat fleas were found on this large number of persons. 

 It must of course be understood that they did not all come from 

 plag-ue-infected villages. A similar method was adopted by the 

 doctors in attendance on plague patients throughout the province. 

 The clothing of 1,829 persons (of whom 393 were plague-infected) 

 was examined between 9th March and 30th November and there 

 were found PecUculus Jiommis and P. capitis (7,641), Acarina (1), 

 Cimex rotundatus (72), Pulex irritans (30) and Xenopsylla 

 cheopis (7). No fleas were found if the inhabitants of plague- 

 infected houses had changed their clothes, and although they 

 afford some opportunity for the transmission of rat fleas, the 

 ordinary measures taken, that is to say, disinfection and isolation 

 reduced this chance almost to nothing. The result of these 

 investigations at the disinfecting station in Malang shows, in the 

 author's opinion, that human intercourse can hardly be of any 

 importance in the spread of plague iri Java. The dwellers in 

 hotels, military hospitals and private houses were frequently 

 observed to be troubled by fleas to such an extent as to cause great 

 discomfort. A number of fleas were captured under these condi- 

 tions and they were found to belong to the species Ctenocejiltaliis 

 fehs or canis, and the author says that it is not at all uncommon in 

 Malang to catch 18 or 20 fleas on one cat. This species of flea is 

 never found on rats from Eastern Java and it was never observed 

 that cats or dogs were attacked by plague. The general conclusion 

 arrived at from these observations are that the siiread of rat 

 plague is mainly due to the house rats being able to get about 

 the country in various ways, the ordinary traffic affording 

 additional facilities. That traffic has a considerable influence in 

 the spread of plague the author thinks is clear from the fact that 

 the first villages to be attacked were those on the main roads. 



Influence of climate. — A large number of observations Avere 

 made upon climatic conditions in relation to the spread of the 

 disease. The results were in the main negative but there Avas 

 some eA'idence that plague spread slowly in low and hot districts 

 if no quick means of transport Avas aA^ailable, possibly due to the 

 fact that fasting fl_eas are shorter liA-ed in hot than in cold 

 districts. 



The author summarises his results as follows : — It Avould 

 appear that the rat flea transmits plague in Eastern Java. 

 Plague immunity among rats is not Avell dcA-eloped in tlmt area ; 

 more so at Sourabaya than at Malang. Plague epidemic is not 

 confined to a certain season, but if the disease already exists the 

 cases tend to increase with a rise in humidity. Heat and dryness 

 of the atmosphere seem to pre\'ent, to a certain extent, the spread 

 of plague. The spread of the disease by the field rat and by 

 i)/«.s decumanus is of small consequence compared with that 

 effected by M. rattus. Human intercourse does not appear to 

 favour the spread of plague, though infection by lice may possibly 

 occur. Rat plague may exist for months Avithout human plague 



