The morning journal-courier., 1908-10-26
ABOUT THE SEXES
Statistics Concerning the Rela- tive Numbers Among the
 Animals.
HOW PROPORTIONS DIFFER
Tn Some Animals the Males outnum- Der the Females and Vice.
 Versa.

What maintains the numerical bal- ances between the sexes? Does this balance hold good fin the case of other living creatures than man? These questions have recently heen studied somewhat and 1t has been discovered that in some cases the numbers of one sex preponderate greatly at birth. This, apparently, Is the case where the preponderating sex is weaker and more apt to die before maturity than the other, and Is device of nature to preserve the balance. Says writer in the Revue Scientfque (Paris July 25)
 Tt Is generally supposed that there is no notable difference in number be- tween the two sexes. This opinion is based especially on the study of man; for In regard to the other animals, observations have never been made on a sufficient number of individuals. Nevertheless, statistics on this point have real value only if they relate to very great number at the moment of birth. for after birth the mortality, in the two sexes is variable, the males, especially among the lower animals. being less resistant and having short- CT lives than the females With man the proportion of males to females is 108 to 100, in 10,S64,s50 cases studied. Quetelet from study of the same ration taken before birth, replaces this figure by 131. Darwin, In 25,560 { horses of English breed found that the proportion of males was a9.7 per cent, Of toad, Bufoleptnosus, Kim ga counted 241 males to 259 females.
 An American author, Montgomery, has been studying the numerical ra- tio of the sexes In a large number of North American spider, the Latrodec- tus mactans. With uncommon pa- tience, he has examined 41,749 young spiders newly born, and he has conn., pleted these observations by study reaches the conclusion that the pro portion of the sexes Is different In | different species. and that 1t may even serve az a specific character In the Lactrodectus the proportion of males ! is S.19; that Is, eight males are born for every female. This fact will per- haps appear odd to naturalists, who are accustomed to find in collections more adult females than males, but this results simply from the compara- l tive logevity of the females.
 How is this high proportion of males in spiders to be explained?
 MT. Montgomery refers 1t to the theory of selection, and he sug- gests a complete theory of sex-orlgln along this line.
 According to this author, In time long past all individuals had the same reproductive faculty, but this was subect to variations or fluctuations. There were some individuals that pos sessed 1t in a greater degree; others in a less. With the aid of selection and segregation, the former became females, the other males. When there is excess of males or qf females selection lntervenes to equalige the proportions. When the two sexes have the same mode of life, when a male can fertilize but one female, the pro- portion of the sexes is equal. When the males are more vigorous than the females and can fertilize more than one, the proportion of males may fall below unity. But when the males are less we'll endowed physically. and psychically, for the struggle for life, when they die frequently before reaching maturity, the number of Translation in the Literary Digest.