458 ELMER L. SHAFFER. 



DESCRIPTION OF FIGURES. 

 PLATE I. (Fics. i TO 12). 



FIGS, i, 2. Spermatogonial chromosome groups, showing macrochromosome 

 pair (A A), the smaller chromosome pairs (BB, CC) and thirteen other chromo- 

 somes showing no size differences. 



FIGS. 3, 4, 5, 6, 7, 8. Metaphase plates of follicle-cells of ovary, showing 20 

 chromosomes (female type). The chromosome pairs (AA, BB, CC) are easily 

 distinguishable. Fig. 8 is late prophase. 



FIG. 9. Metaphase plate from embryonic cell, showing 20 chromosomes hence 

 of female type. 



FIGS. 10, ii. Metaphase plates of ovarian follicle-cells (20 chromosomes) from 

 follicles surrounding old oocytes. Note that the chromosomes are poor in chro- 

 matin content; in Fig. 11 note the precocious longitudinal split of each chromosome. 



FIG. 12. Late telophase of a follicle-cell division in which the macrochromosome, 

 A, is recognizable in the daughter cells. 



