Fig. 236.—Pair of neoteinic royalties, taken from the royal chamber of Termes sp. at Singapore by Mr. G. D. Haviland. The queen was one of thirteen, all in a nearly similar state. A, king; B, C, queen.
A point of great importance in connexion with the neoteinic royalties is that they are not obtained from the instar immediately preceding the adult state, but are made from Insects in an earlier stage of development. The condition immediately preceding the adult state is that of a nymph with long wing-pads; such specimens are not made into neoteinic royalties, but nymphs of an earlier stage, or even larvae, are preferred. It is apparently by an interference with one of these earlier stages of development that the "nymphs of the second form," which have for long been an enigma to zoologists, are produced.
Post-metamorphic Growth.—The increase of the fertility of the royal female is accompanied by remarkable phenomena of growth. Post-metamorphic growth is a phenomenon almost unknown in Insect life, except in these Termitidae; distension not infrequently occurs to a certain extent in other Insects, and is usually due to the growth of eggs inside the body, or to the repletion of other parts. But in Termitidae there exists post-metamorphic growth of an extensive and complex nature; this growth does not affect the sclerites (i.e. the hard chitinous parts of the exo-skeleton), which remain of the size they were when the post-metamorphic growth commenced, and are consequently mere islands in the distended abdomen (Fig. 236, B, C). The growth is chiefly due to a great increase in number and size of the egg-tubes, but there is believed to be a correlative increase of various other parts of the abdominal as distinguished from the anterior regions of the body. A sketch of the distinctions existing between a female of a species at the time of completion of the metamorphosis and at the period of maximum fertility does not appear to have been yet made.
New Communities.—The progress of knowledge in respect of Termitidae is bringing to light a quite unexpected diversity of habits and constitution. Hence it is premature to generalise on important matters, but we may refer to certain points that have been ascertained in connexion with the formation of new communities. The duration of particular communities and the modes in which new ones are founded are still very obscure. It was formerly considered that swarming took place in order to increase the number of communities, and likewise for promoting crossing between the individuals of different communities. Grassi, however, finds as the result of his prolonged observations on Termes lucifugus that the swarms have no further result than that the individuals composing them are eaten up. And Fritz Müller states[[297]] that in the case of the great majority of forms known to him the founding of a colony by means of a pair from a swarm would be just about as practicable as to establish a new colony of human beings by placing a couple of newly-born babes on an uninhabited island. It was also thought that pairs, after swarming, re-entered the nests and became royal couples. It does not, however, appear that any one is able to produce evidence of such an occurrence. The account given by Smeathman of the election of a royal couple of Termes bellicosus is imperfect, as, indeed, has already been pointed out by Hagen. It suggests, however, that a winged pair after leaving the nest do again enter it to become king and queen. The huge edifices of this species described by Smeathman are clearly the result of many years of labour, and at present substitution royalties are not known to occur in them, so that it is not improbable Smeathman may prove to be correct even on this point, and that in the case of some species mature individuals may re-enter the nest after swarming and may become royal couples. On the whole, however, it appears probable that communities of long standing are kept up by the substitution royalty system, and that new communities when established are usually founded by a pair from a swarm, which at first are not in that completely helpless condition to which they come when they afterwards reach the state of so-called royalty. Grassi's observations as to the sources of food remove in fact one of the difficulties that existed previously in regard to the founding of new colonies, for we now know that a couple may possibly bear with them a sufficient supply of proctodaeal and stomodaeal aliment to last them till workers are hatched to feed them, and till soldiers are developed and the community gradually assumes a complex condition. Professor Perez has recently obtained[[298]] the early stages of a community from a winged pair after they had been placed in captivity, unattended by workers. Müller's observation, previously quoted, is no doubt correct in relation to the complete helplessness of royal pairs after they have been such for some time; but that helplessness is itself only gradually acquired by the royal pair, who at first are able to shift for themselves, and produce a few workers without any assistance.
Anomalous Forms.—Müller has described a Calotermes under the name of C. rugosus, which is interesting on account of the peculiar form of the young larva, and of the changes by which it subsequently becomes similar in form to other species of the genus. We represent the development of this larva in Fig. 237. We may call attention to the fact that this figure illustrates the large size of the paunch, which is so extraordinary in some of the states of the Termitidae.
It will be recollected that the genus Calotermes is destitute of workers. There is another genus, Anoplotermes, in which the reverse condition prevails, and the soldier is absent; this is the only case yet known in which such a state of affairs exists. The species is called A. pacificus by Fritz Müller; it differs from other Termitidae in possessing a proventriculus destitute of triturating ridges. The nests of this species are utilised by a little Eutermes (E. inquilinus Müller) for its own advantage; whether by first destroying the Anoplotermes or whether by merely taking possession of the nests abandoned by their owners is not known. It is a most remarkable fact that the Eutermes resembles the Anoplotermes so extremely that the two can scarcely be distinguished, though anatomically they are quite different. The resemblance is indeed so great that it deceived Von Jhering into supposing that the two genera were alternate generations of a single species, one generation possessing soldiers, the other being without them. Subsequently, by anatomical investigation, he recognised[[299]] the error into which he had fallen—an error that, under such peculiar circumstances, was quite pardonable.
Fig. 237.—Changes in external form of the young larva of Calotermes rugosus. A, Newly hatched with nine joints in antennae, × 8; B, older larva with ten joints, × 8; C, next stage with eleven joints, × 8; D, larva with twelve joints; the position of the parts of the alimentary canal are shown—v, crop; m, stomach; b, paunch; e, intestine; r, dorsal vessel, × 16⁄3 (After Fritz Müller.)
Hagen has suggested[[300]] that Hodotermes japonicus never produces winged forms. Very little, however, is actually known as to this species.