“I have, myself, examined over one hundred species of bird embryos, now put up in the museum of Cambridge, and found that, at a certain age, they all have bills, wings, legs, feet, &c., &c. exactly alike. The young robin and the young crow are web-footed, as well as the duck. It is only later that the fingers of the foot become distinct. How very interesting it will be to continue this investigation among the tropical birds!—to see whether, for instance, the toucan, with its gigantic bill, has, at a certain age, a bill like that of all other birds; whether the spoonbill ibis has, at the same age, nothing characteristic in the shape of its bill. No living naturalist could now tell you one word about all this; neither could he give you any information about corresponding facts in the growth of the fishes, reptiles, or quadrupeds of Brazil, not one of the young of these animals having ever been compared with the adult. In these lectures I only aim at showing you what an extensive and interesting field of investigation opens before us; if we succeed in cultivating even a few corners of it we shall be fortunate.” In the evening, which is always the most enjoyable part of our day, we sat on the guards and watched the first tropical sunset we had yet seen. The sun went down in purple and gold, and, after its departure, sent back a glow that crimsoned the clouds almost to the zenith, dying off to paler rose tints on the edges, while heavy masses of gray vapor, just beginning to be silvered by the moon, swept up from the south.