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294 to their nationality, or to what extent it may be so due, we are unable to decide. It is certain, however, that the amount of the disease increases considerably among negroes away from their native countries, an increase that depends in part upon the manner of living. The extent to which a change of climate may operate in that direction will appear from the phthisis mortality among negro troops in the British service at certain military stations.

"Here we have confirmation of the well-known fact, that the migration of the negro to a colder climate is accompanied by a rise in the phthisical average; but it is obvious that we should also make allowance for changed habits of living as weighing not less in the scale. Primer calls attention to a fact that has a bearing on the question, namely, that at Khartoum, in latitude 17° N., with a temperature not lower than that of the mountains around, consumption ensues among negro captives, as well as among the Arabs of the desert, whenever they give up their nomadic life to live under a roof, even if it be in a warmer region.

"Here also an important part among the disease-factors is played without doubt by bad food, insufficient clothing, and confinement in crowded, filthy, and badly-ventilated huts; and there is nothing to surprise us in the experience that consumption has increased to an alarming extent among the negroes of Arkansas of late, or since their emancipation, the result being due, as the