born during the season of greatest abundance, it is equally essential that pairing, which involves great expenditure of energy, should also take place at a season of maximum physical vigor. As an example of the sexual history of an animal through the year, I may quote the following description, by Dr. A.W. Johnstone, of the habits of the American deer: "Our common American deer, in winter-time, is half-starved for lack of vegetation in the woods; the low temperature, snow, and ice, make his conditions of life harder for lack of the proper amount of food, whereby he becomes an easier prey to carnivorous animals. He has difficulty even in preserving life. In spring he sheds his winter coat, and is provided with a suit of lighter hair, and while this is going on the male grows antlers for defence. The female about this time is far along in pregnancy, and when the antlers are fully grown she drops the fawn. When the fawns are dropped vegetation is plentiful and lactation sets in. During this time the male is kept fully employed in getting food and guarding his more or less helpless family. As the season advances the vegetation increases and the fawn begins to eat grass. When the summer heat commences the little streams begin to dry up, and the animal once more has difficulty in supporting life because of the enervating heat, the effect of drought on the vegetation, and the distance which has to be traveled to get water; therefore, fully ten months in each year the deer has all he can do to live without extra exertion incident to rutting. Soon after the autumn rains commence vegetation becomes more luxurious, the antlers of the male and new suits of hair for both are fully grown, heat of the summer is gone, food and drink are plentiful everywhere, the fawns are weaned, and both sexes are in the very finest condition. Then, and then only, in the whole year, comes the rut, which, to them as to most other animals, means an unwonted amount of physical exercise besides the everyday runs for life from their natural enemies, and an unusual amount of energy is used up. If a doe dislikes the attention of a special buck, miles of racing result. If jealous males meet, furious battles take place. The strain on both sexes could not possibly be endured at any other season of the year. With approach of cold weather, climatic deprivations and winter dangers commence and rut closes. In all wild animals, rut occurs only when the climatic and other conditions favor the highest physical development. This law holds good in all wild birds, for it is then only that they can stand the strain incident to love-making. The common American crow is a very good study. In the winter he travels around the ricefields of the South, leading a tramp's existence in a country foreign to