Arneth1 first pointed out that there were significant variations in the nuclei of the polymorphonuclear leukocytes which indicated with some precision the severity of the toxemia in an infectious disease. Unfortunately, his method of classification was so complicated that it afforded no sure basis for clinical work. Cooke2 simplified the classification of the polymorphonuclear leukocytes so that the method can be carried out with comparative ease. In many studies carried out on the blood of adults, it was found that the count in the normal person falls within certain definite limits, and that in persons suffering from infectious conditions it shows characteristic changes. The blood of the new-born infant shows many differences from that of the adult, particularly in the cellular elements. It was therefore considered desirable to classify the types of polymorphonuclear leukocytes in the new-born.
This study is based on a series of sixty new-born