Based upon this general theory of the relation of nutrition to sex-determination, many methods and systems have been devised by as many authorities, and have been followed and promulgated by as many schools. Without going into the almost endless detail which would be necessitated by a synopsis of these various methods and systems, it may be said that they all consist of plans having for their object the decrease of nutrition of the woman in cases in which male children are desired, and the increase of nutrition in cases in which female children are sought for. This increase or decrease in nutrition is enforced for a reasonable period before the time selected for the conception of the child, and also for a reasonable period after the time of conception. The decrease in nutrition does not consist of "starvation," but rather of a "training diet" similar to that followed by athletics, and from which dietary all rich foods, sweets, etc., are absent. In fact, the average dietary advocated by the "Eat and Grow Thin" writers would seem to be almost identical with that of the "male offspring" theorists. Many persons who have followed the methods and systems based on the nutrition theory above mentioned claim to have been more or less successful in the production of the particular sex desired, but many exceptions to the rule are noted, and some writers on the subject are disposed to regard the reported successes as mere coincidences, and claim that the failures are seldom reported while the successes are widely heralded. The present writer presents the claims of this school to the attention of his readers, but without personally positively endorsing the idea. He is of the opinion that the data obtainable is not as yet sufficient to justify the strong claims made for the theory in some quarters; but, at the same time, he does not hesitate to say that there are many points of interest brought out in the presentation of the theory, and that many thoughtful persons seem to accept the same as reasonably well established and logical.