Ploss also tried to draw attention to the fact that better food, in the case of the male as well as of the female parent, could have some effect. Thus, a balance of the numbers of the two sexes depended upon the better or worse harvests in different regions. If an excess of one sex appeared in one year, in consequence of an abundance of food, in the next year unfavorable circumstances raised the number of the other sex, and thus a proportion was reached which represented the normal numbers. According to Fiquet, female calves are born if the cow is poorly fed. This diet should last some weeks, but the bull should be abundantly fed before serving. According to Landois, food plays a most important part in the determination of sex amongst insects. If the germ be richly nourished, females are principally developed. (Landois, ‘_Physiologie_.’) A great number of different foods and drinks, and also substances which have direct medical effects, are commonly known or held to exercise an effect upon the activity of the generative organs, and of these some are also recommended under medical advice. Many of the medicinal substances should be carefully avoided. The use of them may prove deleterious. Cantharides, or various preparations of them, as well as other substances enumerated under this head in pharmacology, are distinctly to be eschewed. Not only are they absolutely incapable of exercising any influence over the sex of the future offspring, but they can also be distinctly injurious to the whole organism, or in any case to the urinary and generative organs in this way, that, after having produced their effect, they occasion a reaction, which leads to abnormal conditions and inflammation of the kidneys. No expedient of this kind, no food of any sort, nor drink, should ever be used, without medical advice. Most of all are these expedients out of place where any question exists of determining the sex of offspring. All these nostrums, as well as the particular kinds of food or drink, exercise only temporarily a certain influence over the activity of the sexual organs, exactly as they do in general over the nervous condition, the mental disposition, humor, etc., which are temporarily stimulated. Herewith may be classed the expedient of the injection of semen recommended by Brown-Sequard, in consequence of which people of advanced age enjoy a feeling of rejuvenescence. His first experiment was tried upon himself, and, in spite of his advanced age, he felt himself quite fresh and young. Originally the injection consisted of a sort of watery extract made from the testicles of animals. Afterwards preparations were used which had been more carefully prepared. These extracts are employed by medical men under the name of spermin or orchidin. In a similar way an attempt was made to obtain extracts and pure preparations from the ovaries of animals (oophorin), which were to be used in the same manner. * * * * *