1 889. J Days and Nights by the Sea. \l\ 
most certainly shown. It is more nearly related to the 
Spiders. 
The case is very different with the ova of many other animals, 
for instance the eggs of prawns such as the Lobster and the 
Shrimp. They are not discharged into the sea, and left to 
take their chances with enemies, but are attached to the body 
of the animal which carries them about until they hatch. In 
most cases they are fastened by fine threads of glue to the 
swimming legs, and as the constant motion of these appendages 
is shared by the eggs, the latter are always well aerated. If 
the ova are removed from the animal, they invariably die. 
Some Crustacea (like the Stomatopods) lay their eggs in 
masses in burrows in the sand or in coral rocks, and if they are 
removed and placed in an aquarium, they also die. But if the 
habits of these animals are studied, it is found that either the 
male or female is always brooding over the eggs and fanning 
them with its legs, thus supplying the needed aeration by the 
currents of water set up. This process of supplying the nec- 
essary oxygen is seen in fish-hatching houses, where the eggs 
are laid upon shallow trays, over which a stream of water is 
constantly passing. 
The eggs of animals like the Corals and Sea-fans can be 
easily obtained in the breeding season, by placing a colony of 
the polyps, like a piece of living coral, in a glass dish or aqua- 
rium. The minute spherical eggs or young will be discharged 
through the mouths of the polyps and float to the surface, when 
they can be skimmed off, transferred to other dishes and their 
development watched. With the modern appliances and 
methods of research, the naturalist of to-day can investigate 
the problems of animal life with far better success than was 
possible a generation ago. How is the life history of an animal 
written ? How do we trace the numerous links in the chain of 
events between the one-called, apparently homogeneous egg, 
to the highly complex animal which produces the egg ? To 
answer this question very briefly we may conveniently select 
the shrimp, although we might choose equally well a fish, a sea- 
urchin or a coral. 
