246 SIDNEY I. KORNHAUSER 



6. All chromosomes divide equationally in the second sper- 

 matocyte division, giving rise to female determining spermatozoa 

 with 11 autosomes and two x-chromosomes, and male determin- 

 ing spermatozoa with 11 autosomes and a y-chromosome. 



7. The y-chromosome of the spermatocyte is chemically and 

 morphologically rather unlike the x-chromosomes during the 

 growth period up until the late strepsinema, when it gives off a 

 nucleolar spherule which takes mitochondrial stains. 



Granvilte, Ohio, June 28, 1921. 



9. BIBLIOGRAPHY 



BRAUNS, FR. 1912. Die Entstehung der Nahrzelle und die Bedeutung derselben 

 fur das wachsende ei bei Forficula auricularia L. ; Sitzungsb. u Abhandl. 

 d. naturf. Gesellsch., Rostock, N. F., Bd. 4 (245). 



CASTLE, W. E. 1921. A New Type of Inheritance. Science, N. S., Vol. 53, 

 No. 1371, pp. 339-342. 



PANTEL, J. 1912. Recherches sur les Dipteres a Larves Entomobies. II. Les 

 enveloppes de 1'oeuf avec leurs d6pendances, des degats indirectes du 

 parasitisme. La Cellule, T. 29, Fasc. 1, pp. 7-289. PL I-VII, 25 text 

 figs. 



PAYNE, F. 1914. Chromosomal Variations and the Formation of the First 

 Spermatocyte Chromosomes in the European Earwig, Forficula sp. 

 Journ. Morph., Vol. 25 No. 4, pp. 559-581, PI. 2, text figs. 7. 



RANDOLPH, HARRIET. 1908. On the Spermatogenesis of the Earwig Anisolabis 

 maritima. Biol. Bull., Vol. 15, No. 2, pp. 111-114. 



STEVENS, NETTIE M. 1910. An Unequal Pair of Heterochromosomes in For- 

 ficula. Jour. Exp. Zool., Vol. 8, No. 2, pp. 227-234, 3 pi. 



ZWEIGER, H. 1906. Die Spermatogenese von Forficula auricularia L. Jena 

 Zeitschrift f. Natur. wiss., Bd. 42, pp. 143-169. 



10. EXPLANATION OF PLATES 



All drawings were made with the aid of a camera lucida. A 1.5 mm. Zeiss 

 apochromatic objective and a 20X compensating ocular was the optical combi- 

 nation used. All figures were drawn at 3300 diameters magnification and subse- 

 quently reduced, in Plate XXIV the reduction being about one-third and in 

 Plates XXV and XXVI the reduction being about two-fifths. 



PLATE XXIV 



Figs. 1-4. Oogonia, metaphase plates, polar view, 26 chromosomes. 



Figs. 5-8. Somatic mataphase plates, polar view from female embryo, 26 

 chromosomes. 



Figs. 9-12. Spermatogonia, metaphase plates, polar view, 25 chromosomes. 



Figs. 13-16. Somatic metaphase plates, polar view from male embryo, showing 

 25 chromosomes. 



