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2. To prevent the spread of the infection, as many rats as possible 
are to be killed. 
3. The period of isolation of suspected patients is not to be less than 
ten days. 
These modified regulations were based upon the experience of several 
years. In carrying out measures of disinfection it is necessary to ex- 
tend the area to be covered as far as possible, as the plague germ is very 
easily propagated. It is also true that bubonic plague often develops 
into that of the pulmonary or pneumonic type and in that event the 
disease not infrequently infects by direct contagion therefore, especially 
in times of epidemic, quarantine and isolation must be strictly enforced. 
It was thought necessary to fix the time of isolation at ten days because 
of the fact that the incubation period of the disease lasts from six to 
seven days. ‘The killing of all rats which it is possible to secure was 
deemed a necessity, as these animals have the closest connection with 
_ plague. The above principles were applied where the intrusion of the 
pestilence was suspected even before the formulation of the new regu- 
lations. 
In attempting to catch rats it is important to remember that traps 
and appliances should be set in all buildings, and it is imperative in 
those which contain cotton and grain, in which the plague germ is most 
liable to be retained. I gave warning in this respect a few years ago and 
as a result the municipal government of Tokyo has passed an ordinance 
respecting buildings and warehouses which provides that all buildings 
must be constructed in a manner to prevent their becoming an abiding 
place for rats. A similar regulation has been adopted in other cities and 
prefectures, especially in those having direct connection with foreign 
countries. These legal acts appear to be rather despotic, but neverthe- 
less they must be deemed necessary in view of the dreadful character 
of the disease which is propagated by these rodents. I believe that the 
extension of similar regulations to dwellings so as to render all of them 
rat proof would in the future generally lessen the danger from the in- 
fection. Such a step has yet to be taken. 
SANITARY WORK. 
The principal undertakings established for the enforcement of  pre- 
ventive measures are (1) bacteriological examinations; (2) search for 
patients; (3) killing of rats, disinfection, and the application of sanitary 
methods; and (4) disposal of patients and of infected articles. The 
work may briefly be described as follows: 
The bacteriological laboratories in the different districts and prefec- 
tures are for the study and diagnosis of plague, and in times of epidemic 
they are used solely for this especial purpose. In such cities as Kobe, 
Osaka, Yokohama, and Tokyo, which are most frequently threatened 
by pest, the Government for several years past has been encouraging 
