Dr. Krauss first published his pioneer investigations in “Kryptadia,” vols. vi. and vii. (Paris, 1899 and 1901); but later he founded an annual for the record of researches into the folk-lore and ethnology of the sexual life, entitled “Anthropophyteia: Jahrbuch für folkloristische Erhebungen und Forschungen zur Entwicklungsgeschichte der geschlechtlichen Moral”--“Anthropophyteia: Annual for Folk-lorist Investigations and Researches in the History of the Evolution of Sexual Morality.” This has been published now for four years, 1904-1907, Krauss having the co-operation of anthropologists, ethnologists, folk-lorists, and medical men, such as Thomas Achelis, Iwan Bloch, Franz Boas, Albert Eulenburg, Anton Herrmann, Bernhard Obst, Giuseppe Pitré, Isak Robinsohn, and Karl von dem Steinen. It constitutes a most important addition to the hitherto very scanty works for the scientific study of sexual problems. Later, I shall have occasion to refer again to this important undertaking. Krauss, who, as he himself says, is insensitive to the romantic appeal of folk-lore, but has an open mind for the realities and possibilities of human history, has proved in this publication the unquestionable existence of sexual promiscuity among the Southern Slavs. As he himself declares, such an abundance of trustworthy proofs, obtained by a professional folk-lorist, regarding the existence of a form of sexual promiscuity within the narrow sphere of a single geographical province of research, has not hitherto been available. It is, moreover, perfectly clear that the human need for sexual variety, which is an established anthropological phenomenon,[159] must in primitive times have been much stronger and more unbridled, in proportion as the whole of life had not hitherto risen above the needs of purely physical requirements. Since even in our own time, in a state of the most advanced civilization, after the development of a sexual morality penetrating and influencing our entire social life, this natural need for variety continues to manifest itself in almost undiminished strength, we can hardly regard it as necessary to prove that in primitive conditions sexual promiscuity was a more original, and, indeed, a more =natural=, state than marriage. For from the purely =anthropological= standpoint--only from this standpoint, since with questions of morality, society, and civilization we are not now concerned--permanent marriage appears a thoroughly =artificial= institution, which even to-day fails to do justice to the human need for sexual variety, since, indeed, vast numbers of men live _de jure_ monogamously, but _de facto_ polygamously--a fact pointed out by Schopenhauer. This criticism is, of course, based upon purely physical sensual considerations; it does not touch marriage as an ideal of civilization possessing a =spiritual and moral= content.