38 A JOURNEY IN BRAZIL. 
long tapering tail of the skate. Were it only that they 
enable us to set aside all arbitrary decisions and base our 
classifications on the teachings of nature, these investigations 
would be invaluable ; but their importance is increased 
by the consideration that we are thus gradually led to 
recognize the true affinities which bind all organized beings 
into one great system." 
April 20th. The day after to-morrow we shall enter 
the Bay of Rio de Janeiro. One begins to see already 
that little disturbance in the regularity of sea life which 
precedes arrival. People are making up their letters, and 
rearranging their luggage ; there is a slight stir pervading 
our small party of passengers and breaking up the even 
tenor of the uniform life we have been leading together 
for the last three weeks. It has been a delightful voyage, 
and yet, under the most charming circumstances, life at 
sea is a poor exchange for life on land, and we are all 
glad to be near our haven. 
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 ascer- 
taining, 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 investiga- 
tions 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 
