Page:Popular Science Monthly Volume 74.djvu/545

Rh hundred. The great majority of these are largely unscientific, the result mostly of philosophical speculation or a priori opinion. As examples of such it was supposed that an egg from the right ovary gave rise to a male and an egg from the left ovary to a female; that the sex of the offspring was like that of the younger or more superior parent; the exact opposite of the latter, that the sex was that of the weaker or older parent; or that the younger or more vigorous parent determined the opposite sex in the offspring; and many others involving equally off-hand assumptions. That the sex of the offspring is that of the weaker parent has been recently advocated again and statistically apparently well supported by Dr. Romme, a well-known physiologist of London. In further support of his theory he cites the fact that among barbarous nations continually at war there is always a preponderance of boys over girls.

Professor Schenck's famous sex-theory is in essence the same. He proposes to increase the physical vigor and the number of the red blood corpuscles in a person when it is the wish to beget a child of the opposite sex. Renewed interest has been aroused in this theory, due to Professor Schenck's connection with the royal family of Russia, where he put his principle to the test with an apparently successful result when the Czarina gave birth to the desired son. But Professor Simon Newcomb, as the result of a very extensive statistical investigation, concludes that "it seems in the highest degree unlikely that there is any way by which a parent can affect the sex of his or her offspring."

Within the last decade students of the problem of sex have become very generally agreed that sex is inherited. In other words, they believe that the same mechanism that provides that an offspring shall have one or the other of a pair of contrasting characters represented in the two parents (a long sharp nose or a short stubby nose, for example) provides also that the animal shall have either the sex of the mother or that of the father. The problem of sex seems to be part and parcel with the general problem of inheritance. Furthermore, characters of the parents are believed to be inherited by the offspring according to Mendelian principles. And it can be shown, as was done by Dr. Castle, of Harvard University, in 1903, that sex may be regarded as the result of a Mendelian segregation, dominance and inheritance of sexual characters. And now it becomes incumbent to explain Mendelian inheritance before continuing the discussion of the problem of sex, seeing that sex appears to be inherited in Mendelian fashion.

Mendelism is the term employed to designate a set of phenomena that appear when animals or plants with sharply contrasting characters (white flower petals and colored petals; gray fur and white fur; short stature and long stature; sagacity and stupidity; etc.) are crossed. The principles included under the term Mendelism were first discovered