VOYAGE FKOM 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 Iarva3 
of a great many insects, and try to raise them ; but as this 
