Elkton, the county seat of Cecil county, Maryland, is a town of 2542 inhabitants, built upon a red clay soil, rather flat as to surface, but sloping gently toward the Elk river. This small stream is not navigable, is but slightly influenced by the tides, and is only about 25 feet below the highest part of the town.

The object of the experiments detailed below, which were made at the suggestion of Dr W. Hunter, was to ascertain whether media containing neutral-red afford a rapid means of detecting Bacillus coli in water and estimating the number present.

The momentous discovery of the part played by Anopheles in the propagation of malaria necessitates careful local inquiries into the prevalence of this genus, in order to ascertain how far the different methods of lessening the amount of malaria which have recently been proposed can be profitably applied to the circumstances met with. In no country are such studies more essential than in India on account of the radical differences in the topographical and climatic conditions of different provinces of this vast and densely populated country, ranging from the waterless deserts of Sind to the steamy, waterlogged marshes of Lower Bengal.

The research which follows was undertaken with the object of determining how far the neutral-red reaction described by Rothberger could be utilised for the purpose of detecting Bacillus coli in water-supplies.

Before proceeding to describe the imago of Anopheles, we wish to record some observations regarding the hibernation of the larvae of various Culicidae. Grassi (1900, p. 47)1 considered that A. bifurcatus hibernated chiefly in the larval form, for he found the larvae of this species in midwinter in Southern and Central Italy, the imagines being rarely encountered. It was quite different with A. maculipennis. In this case the imagines congregated in houses, huts, caverns, etc., whereas no larvae could be found during the winter. Though he assumed that it was so, his finding the larvae in midwinter in the first instance did not prove that they hibernated, for they might well have been derived from late-laid eggs.

The outbreak of Diphtheria which occurred in Cambridge and Chesterton last October and November has already been the subject of a paper in this Journal, which dealt with the facts observed up to January 5th, 1901. The present communication deals with a return of the disease in the Spring of this year.