792
5. The monthly percentage of Anopheles and Culex has been as follows:-
Anopheles.
Culex.
Mosquitoes examined.
Number.
Per cent.
Number.
Per cent.
October,
401
106
26.4
295
73.6
November,
796
50
6.3
746
93.7
December,...
2,342
138
5.9
2,204
94.1
January,
3,380
143
4.2
3,237
95.8
February,
2,524
35
1.4
2,489
98.6
March,
1,586
49
3.1
1,537
96.9
April, May, June,..
3,501
115
3.3
3,386
96.7
5,476
116
2.1
5,360
97.9
3,562
111
3.1
3.451
96.9
July,
2,582
138
5.3
2,444
94.7
August...
2,296
88
3.8
2,208
96.2
September,
2,944
80
2.7
2,864
97.3
Last Quarter, 1900,
3,539
294
8.3
3,245
91.7
First Quarter, 1901,...
7,490
227
3.
7.263
97.
Second Quarter, 1901,.....
12,539
342
2.7
12.197
97.3
Third Quarter, 1901,
7,822
306
3.9
7,516
96.1
The Twelve Months,
31,390
1,169
3.7
30,221
96.3
6. I have arranged these facts regarding Anopheles in the form of a Chart, which I enclose; and through the kindness of Dr. F. J. A. BERINGER, Civil Surgeon, R.A.M.C., I am able to place alongside of them the monthly percentage of cases of Malaria that have occurred among European troops station- ed in Hongkong during the past five years. This Malaria Chart gives the most accurate information possible as to the occurrence of the disease in Hongkong, as it records the incidence of Malaria in large bodies of men who are bound to be either on parade or under careful medical observation. The result is a remarkable testimony to the truth of the Mosquito-Malaria Theory. The Anopheles curve is to a large extent almost parallel with that of Malaria; and consideration of the Malaria curve for the preceding years shows that this is no mere coincidence. The two first of the thirteen months' observations recorded on the Anopheles chart are too high, owing to the fact that some of the more healthy stations did not fall into line till late in October, and I was consequently before that time receiving an undue proportion of insects from the very malarial stations. This requires to be allowed for in comparing the two curves. The Anopheles curve reached its lowest point in February; the Malaria curve reached its minimum, or within a fraction of it, in all the five years shown on the chart in the same month. The Anopheles curve reached its highest point last year in October and this year in July; the Malaria curve reached its maximum in October, 1896, in November, 1897, in August, 1898, in August, 1899, in August, 1900, with a secondary rise in October, and in July of this year (to date).
7. Another noteworthy point in connection with the combined Chart is the sudden drop in both curves from July of this year, when theoretically, and in accordance with previous experience, both should have continued to rise. The facts accounting for this are interesting. On account of the large number of cases of Malaria that occurred in the garrison this year, a general issue of quinine was ordered to all the soldiers, except those in special circumstances where it seemed unnecessary, e.g., at Mount Austin Barracks. This was commenced in August, and at once there is a drop unusual at that season in the Malaria curve. On the other hand, about the end of June at the request of the Captain Super- intendent of Police I drew up a series of simple instructions for the destruction of the larvæ of mos- quitoes and their breeding-places. A General Order embodying these instructions was issued, direct- ing that officers in charge of all police stations should carry them into effect, so far as possible, for their own neighbourhoods. This was done more or less thoroughly from the beginning of July, and the result was a rapid and steady diminution of the Anopheles frequenting the stations. I enclose a copy of my instructions to the police, which were necessarily brief and elementary, in Appendix III. 8. No Anopheles were found among mosquitoes sent to me from the following stations :-
No. 5, No. 6, No. 7, No. 8, Kennedy Town, Mount Gough, Shaukiwan, Tsim Sha Tsui,
Stone Cutters' Island, Hung Hom, and Kat 0.