258 MICHAEL F. GUYER. 



PLATE II. 



From photographs by the author. Enlargement 1,250 diameters unless other- 

 wise indicated. 



All photographs in this plate were made from smears. 



FIGS. 36-39. Metaphases in secondary spermatocytes of the Rhode Island 

 Red fowl showing four chromosomes each. 



FIG. 40. Side view of spindle in a secondary spermatocyte of the Plymouth 

 Rock fowl; one of the four chromosomes has been displaced from its equatorial 

 position, probably in making the smear. 



FIG. 41. A four-chromosomed secondary spermatocyte of a Langshan fowl. 

 X 1,200. 



FIGS. 42-46. Side views of spindles bearing four chromosomes in secondary 

 spermatocytes of the Plymouth Rock fowl. 



FIGS. 47-52. Representative anaphases in the four-chromosomed type of 

 secondary spermatocyte in Plymouth Rock (47, 49), Langshan (48, 50) and Rhode 

 Island Red (51, 52) fowls. 



FIGS. 53, 54. Equatorial plate stages in secondary spermatocytes of Langshan 

 fowls showing four chromosomes each. 



FIG. 55. Polar view of a metaphase in a secondary spermatocyte of a Plymouth 

 Rock fowl showing five chromosomes. 



FIG. 56. One end of an anaphase in a secondary spermatocyte which showed 

 five chromosomes; two of them over lap in the photo so as to look like one. 



FIG. 57. Side view of a five-chromosomed secondary spermatocyte in the 

 Plymouth Rock fowl showing the fifth element, a curved chromosome, at one edge 

 of the spindle. X 1,200. 



FIGS. 58, 59. Stages in the Plymouth Rock similar to that shown in 57. 

 In 58 the curved element lies at the left edge of the equatorial plate, in 59 at the 

 right edge. 



FIG. 60. Anaphase of a dividing five-chromosomed secondary spermatocyte 

 of the Plymouth Rock fowl. X 900. 



FIG. 61. Late anaphase of a dividing five-chromosomed secondary spermato- 

 cyte in a Plymouth Rock fowl. The five chromosomes at the lower pole while 

 not distinctly visible in the photograph are just as distinct in reality as those at the 

 upper pole. Fig. 169 is a camera lucida drawing of this cell which shows its true 

 condition. X 1,450. 



FIG. 62. Slightly different view of same preparation as shown in 61. X 950. 



FIG. 63. A five-chromosomed secondary spermatocyte of the Plymouth Rock 

 fowl, in process of division. The extra chromosome lags at the equator of the 

 spindle until after the autosomes have divided, then it divides. 



FIG. 64. A stage in the Langshan somewhat similar to 63. See Fig. 173 for 

 a drawing of this cell. 



FIG. 65. Side view of a second (anomalous) division of a four-chromosomed 

 secondary spermatocyte in the Plymouth Rock fowl. 



FIG. 66. Anaphase of such a cell as that pictured in 65. 



FIG. 67. Side view of an equatorial plate stage in a four-chromosomed second- 

 ary spermatocyte of the guinea-fowl. X 1,150. 



FIG. 68. Division figure (early anaphase) in an anomalous division of a sperma- 

 tid in which two small-sized chromosomes are going to each pole. See Fig. 198. 



FIG. 69. Material from Plymouth Rock fowl showing (above) an anaphase of 

 a division of a four-chromosomed secondary spermatocyte, and also (below) an 

 anaphase of a second (anomalous) division of such a four-chromosomed cell. 

 X 1,300. 



