47O ELMER L. SHAFFER. 



PLATES VII, VIII, IX. 



Photomicrographs taken at a magnification of about 1,000 diameters, except 

 Nos. 71 and 72 which have been magnified 500. The reproductions here have not 

 been reduced. 



PLATE VII. (Fics. 49 TO 70). 



FIGS. 49, 50, 51. Metaphase plates of follicle-cells of ovary, showing 20 chromo- 

 somes among which the macrochromosome pair can be distinguished. Fig. 51 

 is at a greater magnification. 



FIG. 52. Tripolar spindle in one of the cells of the adhesive gland in the female. 



FIGS. 53, 54, 55, 56. Metaphase plates of first spermatocytes from four different 

 animals, each showing 10 bivalent chromosomes which are similarly grouped in 

 each case. 



FIG. 57. An oblique section through the metaphase plate of the ist maturation 

 division, showing the two halves of the macrochromosome in the center of the 

 complex. 



FIG. 58. Daughter plates cf second spermatocytes, one with 9 dyads, the other 

 with 9 dyads plus the sex-chromosome. Note that the grouping of the chromo- 

 somes is the same as in the first spermatocyte. 



FIG. 59. Giant spermatocyte with a great many bivalent chromosomes and 

 a large amount of mitochondria. 



FIG. 60. Anaphase of first maturation division showing mitochondria sur- 

 rounding spindle. 



FIGS. 61, 62, 63. Various forms of ring tetrad (macrochromosome tetrad) 

 in the early prophases. 



FIG. 64. Macrochromosome tetrad in late prophase. 



FIG. 65. Late prophase of first spermatocyte, showing character of tetrads. 



FIG. 66. Anaphase of first maturation division from smear preparation, showing 

 separation of macrochromosome dyads. 



FIG. 67. Ring tetrad in prophase of first spermatocyte; from smear prepara- 

 tion. 



FIG. 68. First maturation division showing separation of macrochromosome 

 dyads. 



FIG. 69. Anaphase of first maturation division showing separation of the 

 dumb-bell shaped tetrads. 



FIG. 70. Late anaphase of first maturation division, showing lagging sex- 

 chromosome. 



