It has long been recognized that the leukocytes of the circulating blood play an important rôle in many, if not all, bacterial infections, and numerous investigations have already contributed valuable additions to our knowledge of this subject.
The researches of Arneth, calling attention to the morphology of the nucleus in the neutrophil leukocytes, especially in tuberculosis, have stimulated further studies in this direction on the part of various observers. The results reported in this paper were first suggested by the work of Arneth and represent an effort to corroborate and amplify his results by various experimental and clinical observations and especially to determine their value in the diagnosis and prognosis of pulmonary tuberculosis and pneumonia.
It seemed possible that Arneth had laid undue emphasis on the significance of the neutrophil leukocytes and that it was important to study the other forms of leukocytes in connection with them. Pneumonia was