Figure 29. 



A A double nucleus in an erythrocyte from a 6-week- 

 old Single Comb White Leghorn that, 3 days earlier, 

 had received 900r total body irradiation. 



B An atypical erythrocyte found in a nonirradiated bird 

 from the same stock and the same age. 



This again points to the fact that the shape 

 of the cell is not closely synchronized with color 

 change, and not infrequently a cell may show 

 its full complement of hemoglobin and yet re- 

 main as round as an early polychromatic erythro- 

 cyte. Thus, in any attempt to pigeonhole cells, 

 one must select one "chief criterion and let all 

 others become subsidiary to it. Color, in the 

 erythrocyte series, has been selected as the chief 

 criterion, whereas nuclear development, vacuoli- 

 zation of the cytosome, and cell shape are re- 

 garded as subsidiary. This does not minimize 

 the importance or significance of these subsidi- 

 ary criteria. They are indispensible for iden- 

 tification of cells and for an understanding of 

 progressive change, but terminology based on 

 nuiltiple criteria leads to ambiguity and 

 contradictions. 



It was probably some such cell as that repre- 

 sented by figure 19 that led Bizzozero and Torre 

 (1881) to divide erythrocytes into three types — 

 (1) the typical erythrocyte, oval in shape; (2) 

 the type that is spherical but has an oval nucleus 

 and is intensely stained; and (3) a rare type 

 distinguished from the typical erythrocyte by its 

 more delicate contour, weaker staining, and 

 somewhat shorter length, as well as by its larger 

 and sometimes almost spherical nucleus. That 

 type 2 includes immature cells is suggested by 

 the further statement that these spherical forms 

 appear somewhat more abundantly in the blood 

 of anemic animals and correspond to an earlier 



developmental form found in bone marrow. 

 Their type 3 might be a thrombocyte, since throm- 

 bocytes are not othenvise mentioned in their 

 paper. 



Reticulocytes have been mentioned occasion- 

 ally in avian literature. Magath and Higgins 

 (1934) found that the percentages of reticulo- 

 cytes for adult mallard ducks varied from 16.6 to 

 27.7 percent. This is considerably higher than 

 the normal value of 1.47 percent given for chil- 

 dren of various ages (Osgood, Baker, and Wil- 

 helm, 1934). Wills (1932) demonstrated that 

 ni pigeons, reticulocyte counts do not remain at 

 a steady and low level. Individual birds showed 

 high counts during the holding period, for no 

 accountable reason. Peabody and Neale ( 1933 ) 

 had a somewhat similar experience. During 25 

 days confinement, the counts usually fell from 

 15-22 percent to 8-10 percent, but in some 

 individuals the counts went up again to 11-13 

 percent. To our knowledge no one has as yet 

 carried out a study on the changes in reticulocyte 

 counts in birds from the day of hatching to ma- 

 turity, such as was done by Orten and Smith 

 (1934) on rats. According to Magath and Hig- 

 gins, the reticulations in the avian erythrocyte 

 are composed of little dots along the strands of 

 a basket network. As the cells grow older, the 

 network disappears, leaving a few strands and 

 dots. 



Their description agrees closely with the cytol- 

 ogy of this stage as observed in the day-old 

 chick, where at first (fig. 20) there was an abun- 

 dance of granules arranged on a reticulum. 

 These form a band of uniform width around the 

 nucleus, and when cells of this type are given a 

 counterstain it is evident that the cell, if the re- 

 ticular granules had not been revealed, would 

 be classed as a mature cell (fig. 21), but others 

 with reticulations appear to he late polychro- 

 matic erythrocytes. During the final step in the 

 maturation of the cell die reticulum breaks apart 

 and the amount grows less, but it still retains the 

 perinuclear arrangement (fig. 22) and later be- 

 comes dissipated throughout the cytosome (fig. 

 23). It was hoped that the last stages in the 

 disappearance of the reticular granules could be 

 traced, but with the technics used (ch. 7, p. 230), 

 there always persisted a certain amount of pre- 

 cipitate over the slide, which, as it fell on the 

 cells, resembled in size and color those granula- 

 tions. These illustrations for reticulocytes are 



27 



