eight, nine, etc., respectively, and these reveal the nature of the emotion that normally belongs to those years. The various kinds of observations extend over the entire periods of infancy, childhood, and into adolescence, and are very well distributed in number among the years of these periods, although more cases were reported for the years 4 to 8, and 12 to 15, both inclusive, than for the years of the period between 8 and 12. The reason for this becomes clearly apparent later. Analysis of the data contained in all of this material reveals the fact that the emotion of sex-love may appear in the life of the child as early as the middle of the third year. From its appearance at this early age it can be traced in its development through five more or less well marked stages whose time limits are as follows: the first stage extending, as a rule, from the age of three years to the age of eight years; the second from eight to fourteen; the third from fourteen to maturity at about twenty-two in women and twenty-six in men; the fourth from maturity to senescence, whose limits vary widely; the fifth extending through senescence. Not every individual passes through all five stages. Individual differences also keep the time limits of the stages from being exact. CHARACTERISTICS OF THE FIRST STAGE. The presence of the emotion in children between three and eight years of age is shown by such action as the following: hugging, kissing, lifting each other, scuffling, sitting close to each other; confessions to each other and to others, talking about each other when apart; seeking each other and excluding others, grief at being separated; giving of gifts, extending courtesies to each other that are withheld from others, making sacrifices such as giving up desired things or foregoing pleasures; jealousies, etc. The unprejudiced mind in observing these manifestations in hundreds of couples of children cannot escape referring them to sex origin. The most exacting mind is satisfied when to these observations are added the confessions of those who have, as children, experienced the emotion to a marked degree of intensity, and whose memories of childhood are relatively distinct. We are prone to refer many of the manifestations enumerated to imitation. Imitation can account in part for the _form_ in which the emotion shows itself, whose _presence_ is established by the accumulation of a vast amount of evidence. Imitation plays an important role in the development of the sex instinct, and love between the sexes as one of this instinct's derivatives, as it does with the development of most other instincts. It would be no more satisfactory to account for these manifestations by referring them to imitation than it would to account for the love for dolls, the instinct of hunting, the interest in “playing house” by reference to the same cause. When we observe in young puppies, shoats, squirrels, seals, grouse, partridges, field-sparrows, starlings, wood-larks,