INSECTS
forms a body, or soma, the so-called parent. Both the body, or somatic, cells and the germ cells are formed from a single primary cell, which, of course, is usually produced by the union of two incomplete germ cells, a spermatozoon and an egg. The primary germ cell divides, the daughter cells divide, the cells of this division again divide, and the division continues indefinitely until a mass of cells is produced. At a very early stage of division, however, two groups of cells are set apart, one representing the germ cells, the other the somatic cells. The former refrain from further development at this time; the latter proceed to build up the body of the parent. The relation of the somatic cells to the germ cells may be represented diagrammatically as in Figure 62, except that the usual dual parentage and the union of germ cells is not expressed. The sexual form of reproduction is not necessary with all lower animals, nor with all generations of plants; in some insects the eggs can develop without fertilization.
The fully-developed mass of somatic cells, whose real function is that of a servant to the germ cells, has assumed such an importance, as public servants are prone to do, that we ordinarily think of it, the body, the active sentient animal, as the essential thing. This attitude on our part is natural, for we, ourselves, are highly organized masses of somatic cells. From a cosmic standpoint, however, no creature is important. Species of animals and plants exist because they have found ways and means of living that have allowed them to survive, but the physical universe cares nothing about them—the sunshine is not made for them, the winds are not tempered to suit their convenience. Life must accept what it finds and make the best of it, and the question of how best to further its own welfare is the problem that confronts every species.
The sciences of anatomy and physiology are a study of the methods by which the soma, or body, has contrived to meet the requirements imposed upon it by the unchanging laws of the physical universe. The methods adopted are as
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