1905-6.] Studies in Immunity : Theory of an Epidemic. 493 
deaths (diagram X.). The general correspondence shows that the 
deaths may, in the case of smallpox at least, be taken as giving 
Diagram IX. 
a fairly accurate representation of the course of the epidemic. 
With the exception of measles, this exhausts the diseases truly 
Each abscissal unit equals four weeks. 
epidemic in this country. An example of the latter * in Glasgow 
in 1808 is given in diagram, and is seen to conform to the general 
* Watt, Treatise on the Chincough , p. 368. 
