H. Waite 
427 
Again, suppose m = 5 and that a has such a value as will make n = 1, i.e. 
j^„ = l ora = 38400. 
We now have r = -2063 and rm = V0315 ; hence rm>n; or the number of 
recoveries exceeds the number of new cases and the value of m decreases 
continuously. 
From the curve connecting these quantities (Diagrams I and II), we see at 
a glance the value of m corresponding to any given value of a and we gather that 
any appreciable change in the number of anophelines will involve a corresponding 
gradual change in the number of cases ; or, in other words, that, given any 
definite number of anophelines per thousand of the population there is a particular 
malaria rate which will ultimately be reached by a gradual change in the 
value of m. 
Number of Infected Persons. 
Diagram I.* A. Stable Population Curve, Part 1. B. Curve of Equation (ii) p. 429. 
* See p. 429, for the construction of these curves. 
