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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
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