VOYAGE FROM NEW YORK TO RIO DE JANEIRO. 39 



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 bloodvessels, 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 ex- 

 amining 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." 



The lecture concluded with some advice as to observing 

 and recording the metamorphoses of insects. " Though 

 much has been written on the societies of ants and other 

 like communities in Brazil, the accounts of different natu- 

 ralists do not agree. It would be well to collect the larvae 

 of a great many insects, and try to raise them ; but as this 



