On Tuesday the lecture was upon the formation and growth of the egg; a sort of practical lesson in the study of embryology; yesterday, upon the importance of ascertaining, at the outset, the spawning season of the animals in Brazil, and the means to that end. “It will often be impossible for us to learn the breeding season of animals, a matter in which country people are generally very ignorant. But when we cannot obtain it from persons about us, there are some indications in the animals themselves which may serve as a guide. During my own investigations upon the development of the turtles, when I opened many thousands of eggs, I found that in these animals, at least, the appearance of the ovaries is a pretty good guide. They always contain several sets of eggs. Those which will be laid this year are the largest; those of the following year are next in size; those of two years hence still smaller, until we come to eggs so small that it is impossible to perceive any difference between their various phases of development. But we can readily tell whether there are any eggs so advanced as to be near laying, and distinguish between the brood of the year and those which are to be hatched later. When the eggs are about to be laid the whole surface is covered with ramifying blood-vessels, and the yolk is of a very clear bright yellow. Before the egg drops from the ovary this network bursts; it shrivels up and forms a little scar on the side of the ovary. Should we, therefore, on examining the ovary of a turtle, find that these scars are fresh, we may infer that the season for laying is not over; or if we find some of the eggs much larger than the rest and nearly mature, we shall know that it is about to begin. How far this will hold good with respect to alligators and other animals I do not know. I have learned to recognize these signs in the turtles from my long study of their embryology. With fishes it could hardly be possible to distinguish the different sets of eggs because they lay such numbers, and they are all so small. But if we cannot distinguish the eggs of the different years, it will be something to learn the size of their broods, which differs very greatly in different families.”