CHAP, XI.] Measures to prevent the spread of infection by sea. 369 special peculiarities of plague, and in accordance with modern scientific views regarding sanitary precautions for the prevention of the spread of epidemic disease. Important points of difference. The following are the most important points in which the Con- vention of 1897 differs from the previous Conventions on which it is based:- (i) The fact that the period of incubation in the case of plague may be considerably longer than in the case of cholera led to several important modifications. By the Venice Conference of 1892 the period of incubation for cholera was fixed at five days. The conference of 1897 adopted a ten days' incubation period for the purpose of plague regulations. (ii) The list of articles of commerce which may be considered "susceptible" was considerably increased; but it is left to the option of the Governments concerned to allow or prohibit the importation of the commodities, on the "susceptible" list, no article being subject to absolute prohibition. (iii) Modern principles of disinfection were substituted for the obsolete system of land quarantine, but, with a view to meet the wishes of Governments who may find it difficult to thus protect their borders, the option is given of closing the frontiers to travellers and merchandise. (iv) The provisions of the Paris Convention on the subject of the regulation of the pilgrim traffic were embodied in the Venice Convention, but in several respects those provisions were altered in the directions for which the Government of India have from time to time contended. Measures for the prevention of plague to be adopted outside Europe. Notification. The first chapter of the regulations prescribed by the Conven- tion deals with the measures for the prevention of plague which are to be adopted outside Europe. In the first place, it is laid down that the Governments which adhere to the Convention are to notify to other Governments the existence of plague within their several jurisdictions, and must communicate to them a statement of the measures that are being carried out to prevent its diffusion. This requirement as to notification is, however, subject to certain import- ant conditions. Thus the area to be deemed infected is strictly limited to the actual district, town, village, etc., where the disease prevails; and no locality is to be deemed infected merely on account of the importation into it of a few cases of plague which have led to no diffusion of the malady. It is also provided that any area in which plague has existed will cease to be considered as infected 47