A publication appeared in the year 1786 dealing with the above-mentioned theory, and at the time attracted much attention. It has now become difficult to procure, and is often mentioned on account of its containing much that is valuable for influencing sex, both amongst men and animals, that has been gathered from all the authors of the previous century, and more especially from all the ancient authors who had written on this subject. The author was J. Ch. Hencke, organist at Hildesheim, and the title of his book, ‘The Secret of Nature Completely Discovered, both in the Procreation of Man, and for the absolute choice of the Sex of Children.’ Brunswick, 1786. (_Völlig entdecktes Geheimniss der Natur, sowohl in der Erzeugung des Menschen als auch in der willkürlichen Wahl des Geschlechts der Kinder._ _Braunschweig, 1786._) The author relies upon exploded theories, according to which the offspring is evolved, as it were, out of a mixture of the generative secretions of the two sexes, and can be induced to develop into either a male or female individual. Thus the sex is not previously determined, only in the course of its development out of the developing mass, which consists of a mixture of male and female generative secretions, distinctive sexual characteristics make their appearance, according to the predominance of the male or female portion of the mixture. But here, also, the old theory is set forth very precisely. The generative matter of the right testicle serves to fructify ova from which males are developed, that of the left testicle is used to fructify and develop female ova. Similarly, the tenet is propounded that the right ovary contains male ova and the left such only as will, when developed, produce female offspring. * * * * *