The egg of the Earthworm is never deposited in a well-formed nest. As a rule each specimen is found at a greater or lesser distance from its neighbour. As it is not laid in the open air, on the branches of trees (as the eggs of many insects are), or on the surface of the soil, like the eggs of the Ostrich or Peewit, but in damp places under the bark of trees, under stones by streams and ponds, or deep down in the moist soil, special provision has to be made for its development amid such peculiar surroundings. Or perhaps it would be more correct to say, that as the conditions differ so does the provision for meeting them.
If the eggs of a bird or fowl be varnished so as to exclude the air, or if they are enclosed in vessels, or buried in soil at a considerable depth, the young will never be hatched; yet here is an egg which can only be hatched when it is kept moist and cool, and one which may be buried at a depth of some inches, or even feet, in earth or under water, and yet retain its vitality.
The egg of the Earthworm is seldom more than a quarter of an inch in length, and, as it is usually oval, the shortest diameter is only about half that length. It was long ago pointed out that eggs almost invariably remain during the hatching period the same size as they were when first extruded, but here is a curious exception to the rule. We should look with amazement on a Pigeon's egg which increased in size till it became as large as a hen's egg during the time when the mother bird was sitting upon it, but this is exactly what happens in the egg before us during the hatching period. It both lengthens and widens, and we shall have to enquire how this is possible.
The naturalist is already well aware of the fact that when an animal regularly lays a large quantity of eggs of minute dimensions, the offspring is almost invariably unlike its parent, and has to undergo sundry transformations, changes, and developments before arriving at any degree of perfect resemblance to the adult form. Conversely, as in the case of birds, when a few relatively large eggs are laid the young usually emerges with a strong resemblance to its progenitor. The reason is obvious. A good deal of material is needed within the egg in order that a perfectly developed brood may emerge, and when the parent is compelled, through the struggle for existence, to launch a bevy of young on the sea of life, it cannot possibly fill the pockets of each (to speak
