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so much fatality to them and seek shelter in another place. The flight assumes the character of a more or less orderly retreat. It is not so much the spreading out in a circle in every direction, though this occurs to a greater or lesser extent, but it mainly consists in a distinct line of march, the majority following the lead of the few. In the Thana district in Western India the rats' progress was observed to be from south to north; in Bombay it was from cast to west and then to the north, and in Karachi it was from west to east. In some cases this migration in a particular direction explains the immunity of a village or town separated only by a river or stream or not separated by any such barrier from a severely infected locality. Rats migrating are likely to carry with them the germs of plague, which set up in time in the new locality a fresh epizootic. Thus, in a healthy district adjacent to an infected one, there may be noticed first of all a great immigration of rats, later, a growing sickness and mortality among the rats in isolated groups, and then still later a general epizootic among the rats. The migration is neces- sarily limited in extent and slow in its progress, and it is because of these qualities that it can be dealt with effectually.

Plague is not a highly infectious disease in the sense that small pox, scarlet fever, or spotted typhus are, and the measures which have been proved effective against the spread of the latter disease have proved a signal failure in the case of plague. Why? Beenuse neither small pox, scarlet fever, nor typhus are diseases of house vermin ; plague, on the other hand is, and therefore unless we can eliminate this element in the sanitary problem, all other efforts are bound to be futile. Eliminate this element and the sanitary measures effective in these other diseases will be even more certainly and promptly efficacious in plague. Destroy rats and mice, and plague will be a manageable disease; above all, destroy them in anticipation of the importation of plague.

The measures of destruction must be directed not only to the locality in which the rats are dying but also to the adjacent localities, and the disposition of the rats to migrate should be carefully borne in mind, so that on the first appearance of this phenomenon, the rats coming into a healthy locality may be destroyed.

Whatever methods may be adopted for killing rats, the dead rats should not be removed until boiling water, carbolic acid, or corrosive sublimate has been thrown plentifully over their bodies; on no account should they be removed while warm, without these precautions: They should be disposed of by burning. This may be done by removing them, under the precautions mentioned, tu a place adapted for the purpose, or they may be burnt without reinoval by covering them with straw and pouring on them kerosine or other inflammable oil.

February 10th, 1900.

W. J. SIMPSON, M.D., F.R.C.P.

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Reference :-

C.O.885

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