urface of such a cut from
seventy to seventy-five eggs; and estimating the entire number of eggs
according to the number contained on such a surface, I found that there
were not less than eight millions of eggs in the whole string. The
fertility of these lower animals is truly amazing, and is no doubt a
provision of Nature against the many chances of destruction to which
these germs, so delicate and often microscopically small, must be
exposed. The higher we rise in the Animal Kingdom, the more limited do
we find the number of progeny, and the care bestowed upon them by the
parents is in proportion to this diminution.

The next class in the type of Articulates is that of Crustacea,
including Lobsters, Crabs, and Shrimps. It may seem at first that
nothing can be more unlike a Worm than a Lobster; but a comparison of
the class-characters shows that the same general plan controls the
organization in both. The body of the Lobster is divided into a
succession of joints or rings, like that of the Worm; and the fact that
the front rings in the Lobster are soldered together, so as to make a
stiff front region of the body, inclosing the head and chest, while only
the hind rings remain movable, thus forming a flexible tail, does not
alter in the least the general structure, which consists in both of
a body built of articulated rings. The nervous swellings, which were
evenly distributed through the whole body in the Worm, are more
concentrated here, in accordance with the prevalent combination of the
rings in two distinct regions of the body, the larger ones corresponding
to the more important organs; but their relation to the rest of the
organization, and their connection by nervous threads with each other,
remain the same. The respiratory organs, which in most of the Worms were
mere vesicles on the lower part of the sides of the body, are here more
highly organized gills; but their general character and relation to
other parts of the structure are unchanged, and in this respect
the connection of the gills of Crustacea with their legs is quite
significant. The alimentary canal consists of a single digestive cavity
passing through the whole body, as in Worms, the anterior part of which
is surrounded by a large liver. What is true of the Lobsters is true
also, so far as class-characters are concerned, of all the Crustacea.

Highest in this type are the Insects, and among these I include Spiders
and Centipedes as well as Winged Ins