30 MORPHOLOGY OF THE FORMED ELEMENTS 



kilocytosis. Nucleated red cells (erythroblasts) occur in certain 

 abnormal conditions, as in severe cases of anemia and after con- 

 siderable hemorrhage. In the very young nucleated red cells 

 may be normally found, they may be numerous in the dog and 

 cat. A few nucleated red cells have been found by Sherrington 

 and by Traum in adult dogs and by Sherrington in adult cats. 

 Nucleated red cells of the average size are called nortnoblasts, 

 those considerably smaller than the average are microblasts, those 

 considerably larger than the average are megaloblasts. Under 

 certain conditions one meets with red corpuscles that take the 

 stain irrcgularl}^. They may take the basophile stain in small 

 punctae, the corpuscle presenting a coarsely stippled appearance, 

 which is called punctate basophilia. Sometimes corpuscles appear 

 darker, taking some of the basophile stain diffusely. This condi- 

 tion is known as polychromasia or polychromatophilia. Punctate 

 basophilia and polychromasia have been observed in the circulat- 

 ing blood of young animals that were apparently in perfect health. 

 In adults it is not usual to find these changes present except in 

 cases where there is a rapid formation of red corpuscles, as after 

 severe hemorrhage. Walker regards the red corpuscles that take 

 a basophile tint as being younger forms than those having a greater 

 amount of hemoglobin. 



LEUCOCYTES 



In fresh blood the leucocytes are distinguished by being color- 

 less, somewhat refractive bodies of a spherical or irregular form. 

 Some have a rounded nucleus and hyaline or refractive cell bodies. 

 These ordinarily show but little if any ameboid movement. Others 

 have irregularly shaped nuclei and granular cell bodies. The 

 granules in some are minute, showing as dark points; in others 

 the granules are larger, appearing as refractive bodies having a 

 greenish tint. The cells with granules possess active ameboid 

 movement. The several varieties are best distinguished in stained 

 preparations. 



NORMAL VARIETIES OF LEUCOCYTES 



Five normal varieties are found in the circulating blood of the 

 domesticated animals and are differentiated in stained prepara- 

 tions by the following characters. 



