376 EXPERIMENTAL INFECTIONS DURING LIFE 



leucocytes have only a few very minute coccal-shaped 

 oxyphile granules, the nucleus is polymorphous. The 

 eosinophile cells are large cells up to 20^, the cyto- 

 plasm is basophile and contains coarse coccal-shaped 

 oxyphile granules, and the nucleus is often much 

 divided. 



Fowl. The red cells are oval nucleated discs about 

 I2/JL by 6/*, the nucleus being relatively small (about 

 4fi long), irregularly elongated or oval; round, more 

 deeply stained cells with round or diffuse nuclei, also 

 free nuclei and degenerated forms of red cells are often 

 present. The granules of the cells corresponding to 

 the polymorphonuclear leucocytes are rod-shaped, often 

 beaded or with clubbed ends. The nucleus is not 

 polymorphous, but usually divided into two, though 

 it may be single. The cells probably corresponding to 

 eosinophile leucocytes have fine coccal-shaped granules, 

 faintly staining eosinophile or neutrophile. The baso- 

 phile granules of the "mast" cells are coccal-shaped, of 

 various size often quite powdery. 



Pigeon. Red cells resemble those of the fowl, and 

 similar varieties of appearance may be noted. The 

 granules of those cells which correspond to polymorpho- 

 nuclear leucocytes are rod-shaped, but smaller and 

 finer than in the fowl, and do not show clubbed ap- 

 pearances. The nucleus is not polymorphous, and only 

 occasionally divided. The coccal-shaped granules of 

 the eosinophile cells are stained more deeply oxyphile 

 than those of the corresponding cells of the fowl. 



The preparation of dried films for this histological 

 examination of the blood is carried out as follows : 



i. Small samples of blood for the preparation of 

 blood films are most conveniently obtained from the 

 veins of the ear in most of the ordinary laboratory 

 animals, viz., monkey, goat, dog, cat, rabbit, guinea- 

 pig ; in the pigeon and fowl the axillary vein should be 

 punctured; in the rat and mouse either a vein in the 



