FIG. 1.--These quadruplet daughters were born to Mr. and Mrs. F. M. Keys, Hollis, Okla., on July 4, 1915, and were seven months old when the photograph was taken. Up to that time they had never had any other nourishment than their mother's milk. Their weights at birth were as follows (reading from left to right): Roberta, 4 pounds; Mona, 4-1/2 pounds; Mary, 4-1/4 pounds; Leota, 3-3/4 pounds. When photographed, Roberta weighed 16 pounds and each of the others weighed 16-1/4. Their aunt vouches for the fact that the care of the four is less trouble than a single baby often makes. The mother has had no previous plural births, although she has borne four children prior to these. Her own mother had but two children, a son and a daughter, and there is no record of twins on the mother's side. The father of the quadruplets is one of twelve children, among whom is one pair of twins. It is known that twinning is largely due to inheritance, and it would seem that the appearance of these quadruplets is due to the hereditary influence of the father rather than the mother. If this is the case, then the four girls must all have come from one egg-cell, which split up at an early stage. Note the uniform shape of the mouth, and the ears, set unusually low on the head.] "The following is a typical schoolboy anecdote: "'Two twins were fond of playing tricks, and complaints were frequently made; but the boys would never own which was the guilty one, and the complainants were never certain which of the two it was. One head master used to say he would never flog the innocent for the guilty, and the other used to flog them both.' "No less than nine anecdotes have reached me of a twin seeing his or her reflection in the looking-glass, and addressing it in the belief that it was the other twin in person. "Children are usually quick in distinguishing between their parent and his or her twin; but I have two cases to the contrary. Thus, the daughter of a twin says: "'Such was the marvelous similarity of their features, voice, manner, etc., that I remember, as a child, being very much puzzled, and I think, had my aunt lived much with us, I should have ended by thinking I had two mothers!' "In the other case, a father who was a twin, remarks of himself and his brother: "'We were extremely alike, and are so at this moment, so much so that our children up to five and six years old did not know us apart.' "Among my thirty-five detailed cases of close similarity, there are no less than seven in which both twins suffered from some special ailment or had some exceptional peculiarity. Both twins are apt to sicken at the same time in no less than nine out of the thirty-five cases. Either their illnesses, to which I refer, were non-contagious, or, if contagious, the twins caught them simultaneously; they did not catch them the one from the other."