BEVIEW — TROPICAL MEDICINE, ETC. 159 



75 miles. Yet, according to Kitasato, " we can hardly notice any considerable decrease in the number of these Plague — 

 animals in Tokyo." Mosques in Egypt must be treated with respect by the disinfecting gangs, but the manager of continued 



the mosijue is given sublimate solution, so that the mosque servants may carry out disinfection. The most 

 convenient form of hospital hut for rapid building is found to be ten metres long by six metres wide, divided by a 

 partition for the two sexes. 



We now pass to a consideration of the work of the Indian Plague Commission. ^ Con- 

 sidering their experiments and conclusions neriatim, one notes that they found that close 

 contact of plague-infected animals with healthy animals, if fleas are excluded, does not 

 give rise to an epizootic among the latter ; that close contact of young, even when suckled 

 by plague-infected mothers, did not give the disease to the former ; that if the fleas are 

 present, then the epizootic once started, spreads from animal to animal, the rate of progress 

 being in direct proportion to the season of the year and the number of fleas present ; that 

 an epizootic may start without direct contact of healthy animal and infected animal ; 

 that the rat flea can convey plague from rat to rat ; that infection can take place without 

 any contact with contaminated soil ; and that aerial infection can be excluded. 



Another series of experiments carried out in plague houses in Bombay showed : — 



1. Guinea pigs allowed to run free in plague houses in many instances attracted a large number of fleas, 

 which fleas were mostly rat fleas. A certain percentage (29) of these animals contracted plague and died from the 

 disease. The position of the bubo, in the great majority of these cases, was cervical. 



2. If a plague house had been previously disinfected by the ordinary means of disinfection, fleas were still 

 caught in large numbers on guinea pigs set free in them. Further, a considerable number (29 per cent.) of these 

 animals died of plague. The bubo, in the great majority of these cases, was again in the cervical region. 



3. Fleas transferred from plague-infected rats found dead or dying in houses were able to transmit plague to 

 healthy animals in flea-proof cages in the laboratory. The bubo, in all cases, was in the cervical region. 



4. Fleas transferred from guinea pigs and other animals which had been placed for a few hours in plague 

 houses were able to transmit the disease to fresh animals when fed on these in flea-proof cages in the laboratory. 

 The situation of the bubo in these animals was, in the great majority of cases, in the cervical region. 



5. Animals were placed in plague houses in pairs, both protected from soil and contact infection and both 

 equally exposed to aerial infection, but one protected from fleas by means of a fine metallic curtain and the other 

 not so protected. None of the protected animals contracted plague, while several of the unprotected animals died 

 of the disease. The position of the bubo, in every instance, was in the cervical region. 



6. Animals were placed in plague houses in pairs, both protected from soil and contact infection and lioth 

 equally exposed to aerial infection, but one surrounded with a layer of "tangle-foot" and the other surrounded 

 with a layer of sand. The following observations were made : — 



(a) Many fleas were caught on the tangle-foot, a certain proportion of which were found on dissection to 

 contain in their stomachs abundant bacilli microscopically identical with plague bacilli. Out of 85 human fleas 

 dissected, only one contained these bacilli, while out of 77 rat fleas 23 were found thus infected. 



(6) The animals surrounded with tangle-foot in no instance developed plague, while several (24 per cent.) of 

 the non-protected animals died of the disease. 



Work on rat plague is concluded by the following summary : — 



It has been shown that plague rats, like human cases, may be divided into two classes, 

 according as to whether or not a bubo is present. The bubo, if present, is the most 

 important diagnostic sign of plague. 



Of other characteristic appearances, those occurring in the liver of plague-infected rats 

 have been described in detail, since they are of primary importance from the point of view of 

 diagnosis. Hemorrhages in various parts of the body are commonly met with, and an abundant 

 clear pleural effusion constitutes, when present, a noteworthy sign of plague in the rat. 



Analyses of the results of microscopical examination of 1200 plague rats are set forth 

 in the form of tables. It is apparent from these that the bubo gives the best chance of 

 recognising plague bacilli in large numbers. Not only so, but the value of the bubo as 

 an aid in the microscopical diagnosis of plague is inci-eased by the presence in at least 

 50 per cent, of those examined of the characteristic involution forms. 



Eeference has been made to the occurrence of plague-like bacilli or of plague-like diseases 

 in rats. We can only reiterate the statement that in Bombay no difficulty of this kind has 

 been experienced. 



The relative value for diagnosis of the macroscopical and microscopical methods of 

 diagnosis has been discussed. The results of tests carried out for the purpose of comparison, 

 make it manifest that the naked eye is markedly superior to the microscopical method as an 

 aid in diagnosis, and, as the result of our experience, we are prepared to make a diagnosis of 



• " Transference of Plague from Rat to Rat." Journal of Hygiene, September, 1906, Vol. VI. 

 " Further Observations on the Transmission of Plague by Pleas, etc.," July, 1907. Ibid., Vol. VII. 

 "The Epidemic and its Relation to the Epizootics," December, 1907. Ibid., Vol. VII. 



