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of the termite nursery calls for predigested wood pulp; but fortunately this does not have to be supplied from outside--the walls of the house furnish an abundance of raw material and the digesting is done in the stomachs of the parents. The pulp needs then only to be regurgi- tated and handed to the infants. This feature in the termite economy bas a double convenience, for not only are the young inexpensively fed, but the gathering of the food automatically enlarges the home to accommodate the increasing need for space of the growing family. That insects should gnaw tunnels through dead wood is not surprising; but that they should be able to subsist on sawdust is a truly remarkable thing and a dietetic feat that few other animais could perform. Dry wood consists mostly of a substance called cellulose, which, while it is related to the starches and sugars, is a carbo- hydrate that is entirely indigestible to ordinary animais, though eaten in abundance as a part of all vegetable food. The termites, however, are unusually gifted, not with a special digestive enzyme, but with minute, one- celled, cellulose-digesting protozoan parasites that lire in their alimentary canals. It is through the agency of their intestinal inhabitants, then, that the termites are able to lire on a diet of dead wood. The young termites receive some of the organisms with the food given them by their parents and are soon able to be wood eaters themselves. Not all termites, however, are known to possess these intestinal protozoa, and, as we shall see, many of them feed on other things than wood. The termite brood thrives upon its wood-pulp diet, and by December following the spring in which the young were hatched, the members of the new generation begin to attain maturity after having progressed through a series of moltings, as does any other growing insect. But observe, the individuals of this generation, instead of developing into replicas of their parents, have taken on the form of workers and soldiers! However, one should

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INSECTS