It has become possible by means of modern methods of staining to demonstrate a series of changes in the blood of greater or lesser significance and diagnostic importance. The study of the physical and chemical properties of the blood is attended with such difficulties, and is so time-consuming, and its results, further, are of such a general character, that it can not be expected to be of distinctive value. The study of the morphology of the blood, especially of the colorless corpuscles, is, however, more feasible, and productive of better results, and there is reason to hope that a knowledge of the variations in the leucocytes may prove an important and trustworthy aid in diagnosis.
With the object of shedding light on one aspect of this subject, Naegeli1 undertook a study of the blood in more than fifty cases of typhoid fever, making as many as from fifteen to