1. The kinds of bacteria that are isolated by the gelatin plate method from certain river waters freshly polluted with sewage are different from those found in the same water collected a long distance below the point of pollution.

2. In the freshly polluted river water non-chromogenic Staphylococci were found much more abundantly than in the purer waters.

3. In the freshly polluted water the fluorescent bacteria and a group of non-gas-producing, non-liquefying bacteria (Group XI.) were less abundant than in the purer waters.

4. A larger proportion of organisms belonging to the Proteus group were isolated from gelatin plates than from fermentation tubes. The reverse is true of the B. coli and B. lactis aerogenes types. A certain selective influence even upon gas-producing organisms would seem from this to be exerted by the conditions within the fermentation tube.

5. The study of a rather large number of separately isolated cultures belonging to the class of fluorescent microorganisms shows that the differences between the ‘liquefying’ and ‘non-liquefying’ varieties are more constant than is sometimes assumed. The action of these forms upon milk is just as diagnostic as their action upon gelatin. All the strains of fluorescent bacteria that were encountered (58) proved to be motile.

6. Considering as a whole the various physiological tests applied to the several groups of microorganisms, it is found that within almost every group as constituted in the accompanying tables divergence is shown by closely allied organisms in respect to indol formation and reduction of nitrates. The formation of a surface pellicle on broth is also a phenomenon that presents no apparent correlation with more s alient physiological characteristics.

It has long been known that individuals who suffer from such chronic diseases as nephritis and cirrhosis of the liver are very liable to develop an acute infection during the last stages of their illness. These patients rarely die of their chronic ailment. Often in the very last days, or perhaps hours, of the disease pneumonia, a dysentery, an acute endocarditis, or a streptococcus infection sets in, which quickly terminates fatally and must be regarded as the immediate cause of death. So familiar is this course of events that such pneumonias or dysenteries are now known as a fairly definite group of infections, namely, terminal infections. Often they are not recognized before death, but at autopsy their frequency and varying characters have been well shown by Flexner in his statistical and experimental study upon the subject; and though in some cases of terminal septicaemia the portal of entry was not easily found, yet it is important to note how frequently such local infections as leg ulcer or tonsilitis served as a starting point for the general invasion of bacteria. Of still more importance are his observations upon the bactericidal action of the blood of patients who have chronic diseases. The serum from six out of nine such patients showed a distinct decrease in its destructive power toward the Staphylococcus aureus and two of three patients whose serum did not show a diminished bactericidal action left the hospital improved.

That blood or serum and other body fluids, such as the natural or artificially excited exudations, possess bacteriolytic power is a familiar observation.

It is almost impossible to avoid some confusion when one has to deal with diseases which it is difficult to define clearly either by means of symptoms and lesions, or by means of some causal agent capable of demonstration in the majority of cases.

The outbreak which is the subject of the present paper was discovered in the course of an enquiry which is at present being made on the request of the Home Secretary by Mr J. S. Martin, Inspector of Mines, and one of us, into the ventilation of Cornish mines. A number of cases of anaemia had occurred among the miners employed at Dolcoath Mine, Cornwall; and as the anaemia was generally attributed to some defect in the ventilation, this mine, was among the first visited. On examination into the state of the mine, the symptoms of the affected men, and the history of the outbreak, it appeared that the anaemia was almost certainly caused by ankylostomiasis. A more detailed enquiry, in which we have both been engaged, established beyond all doubt the nature of the disease, and has furnished the opportunity of investigating a number of points bearing on the nature and method of spread of ankylostomiasis. A short report on the outbreak has already appeared. We are indebted to Dr S. G. Scott, who has also been engaged in the Home Office Enquiry, for a number of valuable notes as to blood-examinations, and many other details.