432 
Mosquitoes and Malaria 
Example 1, Case (i). p = \000, to,, = 50, (1 = 64000. (The number of anophe- 
lines for a stable population is about 46000.) 
TABLE C. 
{Giving the value of m for consecutive months.) 
Months 
1st Year 
2nd Year 
3rd Year 
4th Year 
5th Year 
6th Year 
1 
53-9 
118-0 
198-8 
258-5 
286-5 
297-7 
58-0 
124-6 
205-0 
261-7 
287-9 
298-2 
S 
02-4 
131 -3 
211-0 
264-9 
289-2 
298-5 
G7-0 
138-0 
216-8 
267-8 
290-3 
299-0 
71-7 
144-9 
222-4 
270-5 
291-4 
299-4 
6 
76-7 
151-8 
227-7 
273-1 
292-4 
299-6 
82-0 
158-6 
233-0 
275-5 
293-3 
300-1 
S 
87-5 
165-5 
238-0 
277-4 
294-3 
300-4 
,9 
93-2 
172-6 
242-6 
279-5 
295-0 
300-6 
10 
99-1 
179-5 
247-0 
281-5 
295-7 
301 -0 
11 
105-2 
186-1 
251-2 
283-3 
296-5 
12 
111-6 
192-6 
254-9 
284-9 
297-1 
Example 1, Case (ii). jj = 1000, mo =50, a =24000. 
TABLE D. 
Months 
1st Year 
2nd Year 
3rd Year 
4th Year 
1 
45-1 
13-8 
5-8 
4-98 
3 
40-7 
12-6 
5-7 
4-96 
3 
36-8 
11-5 
5-5 
4-94 
j 
33-2 
10-5 
5-4 
4-92 
9-6 
5-3 
4-91 
6 
27-2 
8-8 
5-3 
4-90 
24-7 
8-0 
5-2 
4-89 
8 
22-4 
7-4 
5-1 
4-88 
,9 
20-3 
6-9 
5-1 
4-87 
10 
18-3 
6-5 
5-1 
4-87 
11 
16-6 
6-2 
5-0 
4-86 
12 
15-2 
6-0 
5-0 
4-86 
It will be seen from this example that with a comparatively small number of 
infected persons and a quantity of anophelines somewhat in excess of the number 
which would keep the population stable, we get a steady rise in the malaria rate 
until nearly one-third of the whole population are infected; on the other hand, 
the destruction of rather more than half the mosquitoes will produce a fall in the 
rate until the cases are so few that they can be easily and effectively dealt with. 
For the graphs see Diagram IV. 
Example 2. p = 1000, m, = 500, a = (i) 96000, (ii) 48000, (iii) 24000, (iv) 0. 
(The number of anophelines corresponding to a stable population would be about 
89600.) 
