\K\\ 



24 



1903 



No. 4. — CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY 

 OF THE MUSEUM OF COMPARATIVE ZOOLOGY AT HARVARD 

 COLLEGE. E. L. MARK, DIRECTOR. No. 138. 



TJie Heredity of Sex. By W. E. Castle. 



CONTENTS. 



1. Introduction 189 



II. Sex an attribute of eacli ga- 

 mete, and hereditary 190 



III. Principles of heredity appli- 



cable to sex . . . 191 



1. Mendel's law 191 



(a) The principle of domi- 



nance 191 



(b) The principle of segre- 



gation 192 



2. Jlosaic inheritance . . . 192 



IV. Application of the principles 



stated 193 



1. Dioecious and hermaphro- 



dite organisms . . 193 



2. Parthenogenetic organisms 198 

 (a) General application . . 198 



PAGE 



201 

 201 

 202 

 203 



(6) Special cases . . . 



A. Rhodites rosae 



B. Hydatina senta . 



C. Artemia salina 



D. Exceptional parthe 

 nogenesis in Bombyx 

 mori, etc 205 



V. Abnormal sex proportions 



among hybrids . . 205 



1. Relative infertility of cer- 



tain combinations of 

 gametes 206 



2. Coupling of certain sex and 



somatic characters in 



the germ-cells . . . 208 



VI. Summary 214 



Bibliography 216 



I, Introduction. 



A NEW theory of sex is advanced in this paper, yet a theory which in 

 its elements is not new. It is an attempt to correlate three ideas, the 

 correctness of which, separately considered, is generally recognized : 

 (1) the idea of Darwin ('76), that in animals and plants of either sex 

 the characters of the opposite sex are latent ; (2) the idea of Mendel 

 ('66), that in the formation of the gametes of hybrids a segregation of 

 the parental characters takes place, and when in fertilization different 

 segregated characters meet, one will dominate, the other become latent 

 or recessive ; (3) the idea of Weismann ('93) that in the maturation of 

 egg and spermatozoon, a segregation of ancestral characters takes place, 

 and that this segregation' is attended by a visible reduction in the num- 

 ber of chromosomes in the germinal nuclei. 



VOL. XL. — NO. 4 



