A satisfactory explanation is yet wanting for the difference in the changes that take place in the number of leucocytes in cases of typhoid fever on the one hand and of other infectious diseases, notably pneumonia, on the other hand. In the former, when uncomplicated, the number, as is well known, is invariably diminished. while in the latter it is generally increased. It has been demonstrated that a close relationship exists between certain cells of the hemopoietic organs and the cells of the circulating blood. Various alterations in the bone marrow that appear to be absent in cases of other infectious diseases have been observed in cases of typhoid fever, and in this fact may reside, in part at least, the explanation for the phenomena under consideration.
These interesting observations have been confirmed by the results of a comparative study recently made by Dr. Warfield T. Longcope.1 Examination of