Il6 HOWELL. 



EXPLANATION OF PLATE. 



Fig. I. Blood from the heart of a foetal cat, 2.7 cms. long, stained with methyl 

 green, shows the large nucleated corpuscles (ancestral form) and the ordinary 

 circular biconcave mammalian corpuscles. One of the latter is shown with its 

 nucleus escaping. 



Fig. 2. Shows the way in which the nucleus escapes from the nucleated red 

 corpuscle. I, 2, 3, 4, represent different stages of the extrusion noticed upon the 

 living corpuscles; the drawings are colored to correspond with the rest of the figure. 

 a. Specimen from the circulating blood of an adult cat bled four times, b. Speci- 

 mens from the circulating blood of a kitten forty days old, bled twice, c. Specimens 

 from the blood of a foetal cat 9 cms. long. Others from the marrow of adult cat, 

 two of the figures showing the granules present in the corpuscle which have been 

 interpreted erroneously as a sign of the disintegration of the nucleus. All the speci- 

 mens stained with methyl green. 



Fig. 3. Examples of apparent budding of the nucleated corpuscles, resulting from 

 the extrusion of a nucleus from one of the cells after division. From the marrow of a 

 cat. Stained with methyl green. 



Fig. 4. Examples of the large nuclear granules found in the newly formed red 

 blood corpuscles (cat) after severe and sudden bleeding. 



Fig. 5. Multiplication of the nucleated red corpuscles. Methyl green. Marrow 

 of young kitten after bleeding. 



Fig. 6. White corpuscles and blood plates, stained with methyl green, from the 

 blood of an adult cat, bled once to 90 cc, and treated with methyl green and 

 acetic acid. To show the origin of the blood plates from the nuclei of the multi- 

 nucleated leucocytes. 



Fig. 7. Newly formed red corpuscles from section of marrow of femur in a foetal 

 cat 9 cms. Shakespeare-Norris stain of indigo carmine. To show the granules 

 with outline of nucleus seen in the newly formed corpuscles after extrusion of the 

 nucleus and the dissolution of the haemoglobin. 



Fig. 8. Nucleated red corpuscles stained with methyl green, to show the mature 

 and immature forms and the intermediate stages and the colorless erythroblasts. 



Fig. 9. Nucleated red corpuscles from sections of the marrow, stained in hema- 

 toxylin, eosin, and saffronin, to show the preference of the nucleus of the mature 

 form for saffranin, and of the immature form for haematoxylin. 



Fig. 10. Karyokinetic figures of the nucleated red corpuscle, from a specimen of 

 young marrow teased in Flemming's solution, and afterwards stained in saffranin. 



Fig. II. To show the origin of the erythroblasts and nucleated red corpuscles 

 from the embryonic cells (marrow corpuscles). From the liver of a fcetal cat 2.7 

 cms., teased in Flemming and stained in saffranin. 



Fig. 12. To show the marrow corpuscles, a and b with oval nuclei, c and ^/with 

 coiled nuclei; and e, f, with the protoplasm loaded with coarse granules. Specimens 

 teased in Flemming and stained with saffranin. 



Fig. 13. From a section of the liver of a foetal cat 2.7 cms., showing the develop- 

 ment of the liver vessels and the nucleated red corpuscles. To the right of the figure 

 the newly formed vessel contains a number of non-nucleated red corpuscles, sur- 

 rounded in the section by the coagulated plasma. 



Fig. 14. A second section from the same liver. 



Fig. 15. White corpuscles from the blood of a young kitten bled once. Treated 

 with methyl green and acetic acid, to show the origin of the multinucleated from the 

 uninucleated forms. 



