I2O N. M. STEVENS. 



characters. If so we should expect to find an unpaired or an 

 unequally paired heterochromosome in the female of Abraxas 

 where there is sex-limited inheritance in the female, and also to 

 find sex-limited inheritance of some character- or characters in 

 the female of those echinoderms in which Baltzer ('09) and 

 Heffner ('10) have shown that an unequal pair of chromosomes 

 is present in the female. Apparently we have reached a point 

 where the experimental breeder and the cytologist must work 

 together in order to solve the problems of sex-determination, 

 sex-limited inheritance and heterochromosome differentiation. 



BRYN MAWR COLLEGE, 

 December 20, 1910. 



LITERATURE. 

 Baltzer, F. 



'09 Die Chromosomen non Strongytocentrotus lividus und Echinus micro- 



tuberculatus. Arch. f. Zellf., II. 

 Cook, M. H. 



'10 Spermatogenesis in Lepidoptera. Proc. Phila. Acad. Sci., April, 1910. 

 Dederer, P. H. 



'07 Spermatogenesis in Philosamia cynthia. Biol. Bull., XIII. 

 Heffner, B. 



'10 A Study of Chromosomes of Toxopneustes variegatus which show Individual 



Peculiarities of Form. Biol. Bull., XIX. 

 McClung, C. E. 



'05 The Chromosome Complex of Orthopteran Spermatocytes. Biol. Bull., 



IX. 

 Morgan, T. H. 



'10 Sex-limited Inheritance in Drosophila. Science, N. S., XXXII. 

 Randolph, H. 



'08 On the Spermatogenesis of the Earwig Anisoloba maritima. Biol. Bull.. 



XV. 

 Stevens, N. M. 



'06 A Comparative Study of the Heterochromosomes in Certain Species of 

 Coleoptera, Hemiptera and Lepidoptera, with especial Reference to Sex 

 Determination. Carnegie Inst. Pub. No. 36, II. 



'08 A Study of the Germ Cells of Certain Diptera, with Reference to the 

 Heterochromosomes and the Phenomena of Synapsis. Journ. Exp. Zool., V. 

 '10 The Chromosomes in the Germ Cells of Culex. Jour. Exp. Zool., VIII. 

 Wilson, E. B. 



'05 The Behavior of the Idiochromosomes in Hemiptera. Journ. Exp. Zool., II. 

 '09 Recent Researches on the Determination and Heredity of Sex. Science, 



N. S.. XXIX. 



'09 The Chromosomes of Metapodius, a Contribution to the Hypothesis of 

 the Genetic Continuity of Chromosomes. Jour. Exp. Zool., VI. 



