worked with poultry diseases or in the field of 

 hematology have been asked if they had ever ob- 

 served this type of reaction in any of their studies 

 and thus far the answer has always been in the 

 negative. 



Tate and Vincent (1932) have reported the 

 occurrence of sharply delimited spherical bodies 

 in the cytoplasm of erythrocytes of canaries and 

 mice treated with R59 and P25 — two compounds 

 used in antimalarial tests. The bodies stained 

 blue in dried smears following Leishman's stain 

 but were not visible when other types of fixatives 

 were used, and could not be seen in dark field. 

 The peculiar bodies were found, not only in ery- 

 throcytes, but also in eosinophils, leukocytes and 

 reticuloendothelial cells. Their significance is 

 not blown but nothing similar to these bodies has 

 been seen in our studies. Nor were the small 

 spherical bodies called stigmata described by 

 Nittis (1930) after vital staining with brilliant- 

 cresyl-blue observed in our preparations. He 

 found these bodies associated with nucleated 

 erythrocytes of various classes of vertebrates. 

 They were not visible after Wright's stain. Al- 

 though Nittis did not believe that the stigmata 

 were the same as the refractile granule found in 

 nearly mature mammalian erythrocytes by Isaacs 

 (1925) yet the granules resemble each other in 

 appearance as illustrated by the two authors. 



Technic artifacts (figs. 50-72) 



All smears of avian blood will show some de- 

 fective cells. It often becomes a difficult prob- 

 lem to separate those that are atypical jjecause 

 they are truly abnormal from those that have been 

 made to appear abnormal by the technics used 

 to make the smear and stain the blood. Under 

 the previous heading were listed those abnor- 

 malities about which there might be some ques- 

 tion of whether they occurred in situ or were re- 

 lated to the technics used, but the group of cells 

 now to be considered are all quite probably tech- 

 nic defects. Since it is difficult to tell whether 

 a peculiar appearance found in cells should be 

 referred back to the animal or to technic, a rule 

 of thumb has been adopted and found helpful. 

 It is based on the distribution of the abnormal 

 cells on the slide; if a number of cells showing 

 the same defect are grouped in the same region on 



the smear and are absent from other intervening 

 areas, it is concluded that this is a technic defect. 

 The defect shown in figure 50 is commonly 

 found in polychromatic erythrocytes and, there- 

 fore, is quite characteristic for embryonic blood 

 at certain ages (figs. 227 and 273-275) and for 

 leukemic blood. It is readily recognizable by 

 the irregular pale spaces scattered through the 

 cytosome and by a loss of homogeneity in the 

 remaining chromophilic masses of cytoplasm. 

 The spaces are not vacuoles in the cytoplasm or 

 breaks in the continuity of the cell membrane, 

 smce sharp boundaries or refractile margins are 

 never associated with this type of artifact. It 

 occurs predominately in the mid-polychromatic 

 and the early part of the late polychromatic ery- 

 throcyte development. This fact aids in under- 

 standing what causes this atypical reaction. The 

 mid-polychromatic erythrocyte is in a delicate 

 transitional condition. It has lost approxi- 

 mately half of its basophilic substance and has 

 replaced it with about half of its final content 

 of hemoglobin. The transition from basophilic 

 to acidophilic cytoplasm in immature blood cells, 

 like the molting of insects, is a vulnerable period. 

 The cytoplasm is distorted when the smear is 

 dried. The distortion occurs most readily where 

 the serum layer is thick and the slide dries 

 slowly; in thin portions of the smear the cells 

 dry quickly and here the normal homogeneous 

 appearance of the cytoplasm is retained. 



Cells pulled into two pieces have already been 

 shown (figs. 35, 36, and 38) but those illus- 

 trated in figures 51 and 52 differ from them in 

 that the cytoplasm was already fixed before the 

 pulling began or in that the stretching took place 

 when the smear was made. It is obvious in the 

 latter two figures that the cytoplasm had some 

 rigidity before it was forced apart. Cells do 

 not divide normally by the kind of process in- 

 dicated in figures 51 and 52. In both of these 

 cells the nuclei lie at one pole and it is quite 

 probable that these cells were caught in the proc- 

 ess of producing erythroplastids. The cyto- 

 plasm was weakened and the pressure from sur- 

 face tension when the smear was made or when 

 it was blotted was sufficient to pull the halves 

 of the cells apart along the planes already set 

 up for the separation of the cell into nucleated 

 and anucleated portions. 



Price- Jones (1910) studied the differentia- 

 tion of the erythrocyte in the early chick embryo. 



33 



