广西师范大学生命科学学院 普通遗传学-李高岩 1.性别决定 POSSIBLE ACTION OF THE SEX-DETERMINING ECHANISM BY C. E. MCCLUNG ZOoLOGICAL LABORATORIES, UNIVERSITY OF PENNSYLVANIA Communicated by H. H. Donaldson. Read before the Academy, November 20, 1917 Sex is the dual expression in organisms of a common series of characters which are unequally and reciprocally developed in the individuals of the two classes, the essential and primary difference between which is the presence of germ cells of two types-ova in the female, sperm in the male Sex is not a necessity for reproduction or for biparental inheritance: it is required in re- production of highly complex organisms. It exhibits many modifications of appearance and intensity in different groups and ranges from apparent cor respondence of the two classes to wide extremes of dimorphism. While this gradation prevails for organisms in general, the individual is usually fixed in its status of differentiation. In exceptional cases the individual may possess the primary characters of both sexes or may alternately exhibit one or the 第四章性别决定与伴性遗传 Slide 5广西师范大学生命科学学院 普通遗传学-李高岩 第四章性别决定与伴性遗传 Slide 5 1. 性别决定 1902年，C. E. McClung等 人通过对昆虫的研究，揭开了生 物性别决定的奥秘