centiically placed so that the granules lie at one 

 side of the cell. This cell in the mallard duck 

 is extremely susceptihle to aqueous stains; even 

 Wright's stain dissolves most of the granules and 

 when this happens so that the cell contains only 

 a few granules, the nucleus becomes more in- 

 tensely stained and the cell closely resembles a 

 lymphocyte with magenta bodies. Often it is 

 only the pinkish ground color of the basophil 

 cytoplasm and the blue of the lymphocyte that 

 distinguishes one cell from the other. Both May- 

 Griinwald Giemsa and MacNeil's tetrachrome 

 stains dissolve the cytosome and its granules to 

 such an extent that basophils could not be found 

 in smears following these stains. 



SIZE OF CELLS 



Graphs in chapter 2 (figs. 89, 152, 153, and 

 197) give the average sizes of thrombocytes, 

 lymphocytes, monocytes, and the three granulo- 

 cytes. With the possible exception of the cui-ves 

 for the granulocytes, they are unimodal. Ac- 

 tually the data for these graphs represented a 

 composite from four sources: 



Stock from the U. S. Regional Poultry Research Lab- 

 oratory: 



Single Comb White Leghorns, line 6 — relatively 



resistant to lymphomatosis. 

 Single Comb White Leghorns, line 15 — relatively 

 susceptible to lymphomatosis. 

 Stock from a commercial breeder: 

 New Hampshires. 

 Columbian Plymouth Rocks. 



Slides were taken from individuals of each group 

 and the various cell types were measured. 



The most challenging data came from differ- 

 ences in size of erythrocytes. The length and 

 width of the cytosomes and nuclei of 25 cells 

 from each bird were measured. The ranges and 

 the averages are given in table 12. The average 

 length of the erythrocyte for our stock was 10.6m, 

 and the width was about 6.6m ; the nucleus was 

 4.1 X 3.0m. There was little difference between 

 lines 6 and 15. Both breeds of chickens pro- 

 cured from commercial sources had erythrocytes 

 that averaged about 1.6m longer and the nuclei 

 were about 1.0m longer, but the widths of each 

 were the same as for the smaller cells from our 

 birds. Even among the individuals of a group 

 there may be considerable difference in a particu- 



lar set of measurements ; for example, the erythro- 

 cyte nucleus of the first Columbian Plymouth 

 Rock was 18 percent longer than that of the sec- 

 ond one. These data raise again the questions, 

 Wliat is the form of a typical erythrocyte? Are 

 the rounded cells with oval leptochromatic nuclei 

 less mature than the longer cells with rodlike 

 pachychromatic nuclei? 



Keller (1933) studied cell and nuclear size 

 in dwarf and normal breeds of chickens. In em- 

 bryos, during the incubation period of 4 to 8 

 days, there was no significant difference in 

 lengths of erythrocytes. At hatching, the aver- 

 age dimensions of length and width for the dwarf 

 breed was 8.05 x 3.88m and for the breed of nor- 

 mal size, 7.51 X 3.77m. In the grown birds, the 

 dwarf showed 7.84 x 4.19m and the chicken of 

 normal size, 8.19 x 4.50m. It was concluded 

 that the size of the breed had no influence on the 

 size of the erythrocytes. It should be noted that 

 the average values given in her work are in every 

 case less than the minimum of the range given 

 in table 12. 



Kitaeva (1939) also studied the size of 

 erythrocytes from three European breeds of 

 chickens — Langshans, Brown Leghorns, and Ben- 

 thams. The differences were slight. Averages 

 computed from his data on all adult birds were, 

 length 11 .Om and width 6.6m. These values fall 

 within the ranges given in table 12. 



An extensive study of cell size in relation to 

 body weight was made by Melmer (1938) on 11 

 breeds of chickens. He used epithelial cells, 

 striated muscle cells, and erythrocytes. The 

 bird weights varied from 335 to 2900 grams. 

 The area of the erythrocytes varied from 62.3 to 

 77.2 sq. M and, in spite of considerable vari- 

 ability, he obtained a correlation of — 0.54±0.08 

 between body weight and erythrocyte area. He 

 studied size of erythrocytes in the White Leghorn 

 from 1 day of age to 54 montlis of age. Wlien 

 dividing the series into those younger than 9 

 months and those older than 9 months, he ob- 

 tained an average erythrocyte area of 70.0 sq. m 

 for the former and 66.5 sq. m for the latter. 



Kalabukhov and Rodionov (1934), who were 

 interested in the problem of changes in the blood 

 with age, gave the following figures, based on the 

 sparrows Passer montanus L. and P. domesticus 

 L., which have altricial young: age 1-5 days, 

 hemoglobin 4.0 percent, number of erythrocytes 



211 



