REPRODUCTION 1 6 3 



known as a sex-linked recessive. The sons of such a color-blind father 

 will all be of normal color vision (XY) since their single X chromosome 

 comes from the mother. Furthermore, they are incapable of transmitting 

 the defect. When the daughters marry, however, since each carries one 

 defective X, 50 per cent, of their ova will carry this X and 50 per cent. 



will carry a normal X. Married to a man of normal color vision (XY) such 

 women are equally likely to have color-blind sons (XY) or sons with 



normal color vision (XY), since the chances are equal for a Y-bearing 

 spermatozoon to meet either type of ovum. The daughters, on the other 

 hand, will all be of normal color vision, but 50 per cent, of them will, like 

 the mother, be carriers of the defect. If such a carrier (XX), however 

 marries a color-bhnd man (XY), the expectation is that half of the daugh- 

 ters will be color-blind, (XX) and half will be carriers (XX). Also, 50 per 

 cent, of the sons of such a mating will be color-blind (XY), the others, 



of normal color vision (XY). More than twenty sex-linked traits are 

 known in man. Among these may be mentioned hemophilia (excessive 

 bleeding), various eye defects, certain skin abnormalities such as absence 

 of sweat glands, and several neural and mental anomalies. In the hereditary 

 nervous disorders, the sex-linked factor not infrequently supplements an 

 additional factor borne on one of the ordinary chromosomes. 



Evidence of the opposite sex in normal man is seen in the possession of 

 nipples, a minute uterus viasculinus and other rudimentary structures. Since 

 each sex possess the potentialities of the other, either may, under adverse 

 conditions, become intersexual. Cases of intersexuality in some degree are 

 occasionally encountered in both man and domesticated animals. Gener- 

 ally it is a case of an undeveloped male in which, apparently because 

 of the absence of normal testicular hormone, both male and female organs 

 develop to a certain point so that a neutral type results. 



While there is nothing novel about sex and while it will work out much 

 the same generation after generation in a given stock of people, there is 

 little doubt that many of our young folk of today know more of the true 

 facts of sex and have fewer absurd notions and sentimental balderdash 

 about it than did their more recent forebears. They are not going to look 

 on sex as something which, even at its best, is shameful, as something which 

 should be tolerated merely because of its indispensability for the continu- 

 ance of human existence. The chastity couch which intrigued the puritan- 

 ical conscience represents a vegetarian form of love that will find no re- 

 sponse in their marital dietary. As a result they will probably live happier, 

 saner, more wholesome lives than did these apostles of fleshly mortifica- 

 tion. If they make mistakes they will pay the inevitable penalties of lowered 

 ideals, blunted capacity and blighted lives, and not infrequently, of loath- 

 some disease and death. The latter, disease and death, is perhaps the only 

 penalty that will appeal to the less delicately minded of them, but even 



