BIOLOGIC BASIS OF SEX 



tions as background material for a present 

 day understanding of sex determination. 

 The current presentation makes no attempt, 

 except in the barest outline, to repeat this 

 early material other than in those aspects 

 which bear on the advances that have been 

 made since the printing of the second edi- 

 tion. 



Immediately following the publication of 

 the first edition of Sex and Internal Secre- 

 tions there was a resurgence of interest in 

 the problems considered in that book. The 

 resulting research led to notable advances 

 in available knowledge. Seven years later 

 the second edition was published. A second 

 wave of accomplished research appeared. In 

 the interim of the past 21 years extensive 

 advances have been recorded, particularly 

 in understanding the mechanisms of sex dif- 

 ferentiation in plants as well as in many 

 animals. Among others, the data on Melan- 

 drium, Asparagus, Rumex, and Spinacia 

 have been of first importance. Further in- 

 formation on Drosophila, Habrobracon, and 

 Xiphophorus has notably broadened our 

 viewpoints. Beginnings have been made to 

 a better understanding of the conditions for 

 sex separation in bacteria, protozoa, bees, 

 birds, goats, mice, and man. To these spe- 

 cific contributions may be added the basic 

 advances in understanding the methods by 

 which genes are transmitted from one gen- 

 eration to the next, accomplish their actions 

 in development, and by which chromosomes 

 reorganize and reconstruct gene groups. 



The period has also been one of excellent 

 monographic treatments on different phases 

 of the subject. Wilson's The Cell in Devel- 

 opment and Inheritance (1928) and earlier, 

 Morgan's Heredity in Sex (1914), Schra- 

 der's The Sex Chromosomes (1928) and 

 Goldschmidt's Lymantria (1934) retain 

 their pre-eminence. To this list have now 

 been added the publication of extensive 

 tabulations of chromosomes of cultivated 

 plants by Darlington and Janaki Ammal 

 (1945), of animal chromosomes by Makino 

 (1951 ), and the yearly index to plant chro- 

 mosomes beginning with 1956, compiled by 

 a world-wide editorial group and published 

 by the University of North Carolina Press, 

 Chapel Hill, North Carolina. Those volumes 

 give access to the basic chromosomal consti- 



tutions and their sex relations for far more 

 species than were heretofore available. In- 

 heritance information has been made more 

 accessible and at the same time in more de- 

 tail. The tabulations of mutants observed in 

 particular species as in D. melanogaster 

 (Morgan, Bridges, and Sturtevant, 1925; 

 Bridges and Brehme, 1944) have been fol- 

 lowered by those of corn, mouse, domestic 

 fowl, rat, rabbit, guinea pig, Habrobracon, 

 and many other animal forms, together 

 with similar tabulations for cereals and 

 a number of other plant species. Books 

 of particular interest include those of Hart- 

 mann. Die Sexualitdt (1956), White, Ani- 

 mal Cytology and Evolution (1954), Gold- 

 schmidt, Theoretical Genetics (1955,1, 

 Hartmann and Bauer, Allgemeine Biologic 

 { 1953) , and Tanaka, Genetics of Silkworms 

 (1952), and special reviews in various vol- 

 umes of Fortschritte der Zoologie (1 to 12) 

 (Wiese, 1960). Basic normal development 

 of Drosophila has been presented in con- 

 venient book form in papers by Cooper, 

 Sonnenblick, Poulson, Bodenstein, Ferris, 

 Miller and Spencer, Biology of Drosophila 

 (Demerec Ed., 1950) . Special papers hav- 

 ing a direct bearing on the subject matter 

 include particularly those of Pipkin (1940- 

 1960) in analyzing the various chromo- 

 somes of Drosophila for sex loci, of Tanaka 

 (1953) and Yokoyama (1959) for their 

 studies and reviews of the genetics of silk- 

 worms, and of Westergaard (1958) on sex 

 determination in dioecious flowering plants. 



II. Mechanistic Interpretations of Sex 



The records of search for basic mecha- 

 nisms involved in the determination of sex 

 have been foremost in the writings of man 

 from the beginning of historical record. 

 These ideas have included all forms of 

 mechanisms both intrinsic and extrinsic to 

 the organism. The most constructive ad- 

 vance, although not realized at the time, 

 came through the recognition of cell struc- 

 ture, chromosome maturation and the dis- 

 crete behavior of the inheritance. Differ- 

 ences in clu-omosome behavior were noted 

 but not alwaj^s related to facts of broader 

 significance. The period was one of expand- 

 ing observations and development of ideas 

 as they applied to species in general and 



