226 MARY T. HARMAN. 



EXPLANATION OF PLATES. 



All figures were made at table level by means of a Zeiss compensating ocular 

 No. 6 and a 1.5 objective with the aid of a camera lucida. Figures 13, 14 and 15 

 were enlarged three and one half diameters. All others were enlarged two and 

 one half diameters. All were reduced one third. 



PLATE I. 



FIG. i. BC, metaphase plate, lateral view, of spermatogonial division. 



Fig. 2. BC, late anaphase, spermatogonial division. 



FIG. 3. CC, metaphase plate, polar view, spermatogonial division; X is the 

 odd-chromosome, 3, 3 is the third pair of chromosomes, and 2 is one of the chromo- 

 somes of the fifth pair showing a precocious split. 



FIGS. 4 AND 5. CC, metaphase plates, polar view, spermatogonial divisions; 

 3, 3 third pair of chromosomes. 



FIGS. 6, 7 AND 8. BC, metaphase plates, polar view, spermatogonial divisions; 

 3, 3 1 third pair of chromosomes, 3 1 is the hooked chromosome of the third pair. 



FIG. 9. BB, metaphase plate, polar view, spermatogonial division; the numbers 

 i, 1-2, 2, etc., to 6, 6 are homologous pairs of chromosomes, X is the odd-chromo- 

 some. It will be noted that the members of the third pair are both hooked chromo- 

 somes in BB. 



FIGS. 10, ii AND 12. BB, metaphase plates, polar view of spermatogonial 

 divisions, 3, 3 is the third pair of chromosomes. 



