The ovarian system is also simple; there is a variable number of elongate egg-tubes, each of which opens separately into the oviduct; the two ducts unite to form a short uterus, on which there is placed first a spermatheca, and near the extremity a convolute tubular sebific gland. The number of egg-tubes is subject to extraordinary variation, according to the species, and according to the age of the fertilised individual. SOCIAL LIFE.—Termites live in communities that consist sometimes of enormous numbers of individuals. The adult forms found in a community are (1) workers; (2) soldiers; (3) winged males and females; (4) some of these winged forms that have lost their wings. Some species have no worker caste. The individuals of the third category are only present for a few days and then leave the nest in swarms. In addition to the adult individuals there are also present various forms of young. The individuals that have lost their wings are usually limited to a single pair, king and queen; there may be more than one king and queen, but this is not usual. The king and queen may be recognised by the stumps of their cast wings, which exist in the form of small triangular pieces folded on the back of the thorax (Fig. 235). The continuance of the community is effected entirely by the royal pair; they are the centres of activity of the community, which is thrown into disorder when anything happens to them. Usually the pair are physically incapable of leaving the nest, especially the queen, and frequently they are enclosed in a cell which they cannot leave. In consequence of the disorganisation that arises in the community in the absence of a royal pair, Termites keep certain individuals in such a state of advancement that they can rapidly be developed into royalties should occasion require it. These reserve individuals are called complementary by Grassi; when {362}they become royalties they are usually immature as regards the condition of the anterior parts of the body, and are then called by Grassi and others neoteinic, as is more fully explained on p. 380. SWARMS.—As a result of the Termite economy large numbers of superfluous individuals are frequently produced; these, in the winged state, leave the community, forming swarms which are sometimes of enormous extent, and are eagerly preyed on by a variety of animals including even man. Hagen has given particulars[288] of a swarm of _T. flavipes_ in Massachusetts, where the Insects formed a dark cloud; they were accompanied by no less than fifteen species of birds, some of which so gorged themselves that they could not close their beaks.