I5O H. B. GOODRICH. 



whose suggestion and under whose guidance the work has been 



undertaken. 



COLUMBIA UNIVERSITY, 

 May, 1914. 



REFERENCES. 

 Edwards, C. L. 



'10 Idiochromosomes in Ascaris megalocephala and Ascaris lumbricoides. 



Archiv fur Zellforschung, Bd. 5. 

 Payne, Fernandus. 



'10 The chromosomes of Acholla multispinosa. BIOL. BULL., Vol. 18, March. 



EXPLANATION OF PLATE. 



All figures are drawn with a Zeiss 1.5 mm. apochromatic objective, a no. 18 

 compensating ocular and projected with camera-lucida to table level. Figures 

 as here reproduced give a magnification of 3,000 diameters. Figs, i, 2, 3, 7, 8, n, 

 12, 13 are from material fixed in Gilson-Carnoy's fluid and Figs. 4, 5, 6, 9, 10 from 

 material fixed in strong Flemming's fluid. 



FIG. i. ' Spermatogonial metaphase. 



FIG. 2. First spermatocyte metaphase showing the XY group centrally located 

 and surrounded by 13 autosomes. 



FIG. 3. First spermatocyte metaphase. An optical section of a side view 

 showing the Y-chromosome opposite the end of the long X-chromosome, six other 

 X-elements and three pairs of dividing autosomes. 



FIGS. 4, 5, 6. First spermatocyte anaphase. Figures are from one spindle; 

 Fig. 4 showing upper ring of 13 autosomes and Y, Fig. 6 showing lower plate of 13 

 autosomes and gap opposite position of Y in Fig. 4, Fig. 5 showing the intervening 

 X-element of 8 chromosomes. 



FIG. 7. First spermatocyte anaphase. A side view of late stage showing 

 daughter plates of autosomes and X-group viewed edgewise. 



FIG. 8. First spermatogonial anaphase. Late stage showing 5 autosomes from 

 upper plate, 3 from lower and the X-group of 8 chromosomes. 



FIG. 9. Second spermatocyte metaphase showing 14 chromosomes. 



FIG. 10. Second spermatocyte metaphase showing 21 chromosomes. 



FIGS, ii, 12. First oocyte anaphase. Daughter plates from one spindle and 

 each showing 21 chromosomes. 



FIG. 13. Second oocyte metaphase showing 21 chromosomes. 



