There are two opinions in regard to the relationship between the various forms of white blood corpuscles, the one maintaining their genetic distinctness, the other that transition is easy from one form to another, and well-known hematologists are arrayed on either side.
On account of the large size and the staining properties of their granules, the eosinophilous leucocytes have served as the basis of more study than other forms. Their increase in the blood in certain diseases has considerable importance in diagnosis; as is well known, in trichinosis, for example, eosinophilia is very characteristic, but it may occur in other forms of helminthiasis as well. The behavior of eosinophiles in bacterial infections has long been the subject of investigation, and it has been ascertained that in some infections an increase of eosinophiles indicates a favorable outcome, while diminution in number has the contrary significance. In spite of the many researches