The

tion being that this particular species is given to regicide, though this would be contrary to the usual habit of Termites. following table (modified from Grassi) will show the various kinds of individual that have been found in the dwellings of Termes lucifugus:

2. Nymphs that are not
to be concerned with
egg-production.

1. Young, undifferentiated nymphs.

3. Nymphs that will be 4. Reserves for royalties (present if 14,
concerned with egg- 15, and 11 are absent, or 14 and 15
production.
not sufficiently numerous).

When we remember that the societies of this and other species may exist for a very long time, the reason for the production of substitution royalties becomes tolerably clear. We may suppose that a society is in the first instance founded by a fully-developed royal pair, after they have shed their wings. When a sufficient number of workers have been matured to do the ordinary work, the royal pair for the rest of their lives are carefully tended (though possibly in some species the king may be destroyed), being afterwards replaced by substitution royalties, devoid of wings, these being unnecessary under the circumstances. Provision would, of course, be made for a continuous succession of queens and kings of this kind, and the society would only die out when the environment became in some way very unfavourable.

The Light-shunning Termite lives in wood, like the Yellownecked species, but its building operations are much more elaborate. Complex galleries and chambers are tunnelled out, and, as before, the exhausted intestinal pellets are employed in constructive work, the cement being saliva. The same sorts of food are used as in the other species.

The societies of certain Termites native to tropical Africa are the largest and most complex yet discovered, though our knowledge regarding them is unfortunately very incomplete. The most famous species is the Warrior Termite (Termes bellicosus),

which was long ago investigated by Smeathman in West Africa. His description in the Philosophical Transactions for 1781 is astonishingly correct, considering the date at which it was written. Each of the vastly numerous communities constructs and lives in a wonderfully solid dwelling in the form of a mound that may be as much as 20 feet high, and is shaped something like a sugar-loaf. It is chiefly made of earth glued together with saliva, while a good deal of the interior work is carried out with the materials already mentioned for other species. A single

royal couple constitute the centre of social life, and there are both worker and soldier castes, the members of the former being much the larger. The name "soldier" is not altogether a happy one, for it appears that the workers fight much better, while the supposed military individuals are rather fond of looking on. Below the termite dwelling (fig. 1100) are excavations (c) from which earth for building is procured, while the dwelling itself is divided into four stories (A-D), surrounded by a common external wall ( on left), which is traversed by transverse and longitudinal galleries (on right). The centre of the ground-floor (A) is occupied by the royal chamber (r), which is of considerable size, and enclosed by a curved wall in which there are numerous

apertures, giving free access to the workers, and furthering ventilation. The king lives here of his own free-will, while the queen is obliged to be a prisoner, for her abdomen is so filled with eggs as to be of relatively enormous size. Attendant crowds of workers are constantly to be found within the royal chamber, attending to the various wants of the king and queen, and carrying away the eggs, which are sometimes laid at the rate of 60 per minute (fig. 1101). Numerous worker-dwellings (s) adjoin the abode of their titular sovereigns, and the outer part of the ground-floor is

Fig. 1101.-Royal Cell of Warrior Termite (Termes bellicosus), broken open to show queen (Q) and her attendants e (on left), Openings into royal cell; e (on right), an opening that has been closed up; about % natural size.

occupied by numerous store-chambers (m) in which are heaped up gums and other dry vegetable products. The first floor (B) is a large pillared hall, which has no known use except that of serving as an air-space. The second floor (c) may be called the "nursery", for here the eggs are hatched out, and the young nymphs carefully tended. The space is subdivided by means of strong vertical partitions (a), and the central portion is marked off into a large number of small compartments (6), separated from one another by more delicate party-walls (c). The third story or attic is simply an air-space. It will be noted that the arrangements are such as to further the maintenance of equable conditions as regards temperature and moisture, to variations in which Termites appear to be particularly sensitive.

In concluding this chapter it may be noted that the larvæ of many insects are found feeding together in "companies", which have hatched out from batches of eggs laid at the same time and place. Probably the most remarkable case of associated larvæ is afforded by the maggots of certain of the little twowinged flies known as Fungus Gnats (Mycetophilida). One of these is familiar as the " Army Worm" (Sciara militaris) of Europe, and allied forms are native to the United States. The maggots live among rotting leaves, and are sometimes found moving from place to place, united together by sticky threads, and writhing along like a snake. The largest armies of this sort may include millions of individuals, and are stated to reach an extreme length of 100 feet, with a breadth of 6 inches, and a depth of 1 inch. The migrations are probably dependent on the question of food-supply.

CHAPTER LXIII

ASSOCIATION OF ORGANISMS-SOCIAL BACKBONED ANIMALS (VERTEBRATA)

That many backboned animals are of gregarious habit is too well known to require emphasis. Our vocabulary includes many words signifying communities of animals, e.g. we speak of a "shoal" of fishes, a "flock" of birds, a "pack" of wolves, a "herd" of antelopes, and so on. The societies of which the existence is implied by many such words exhibit a type of communal life differing greatly from that described for insects, and one that is in some respects less interesting, except in so far as it throws light on the problems of sociology, with which all intelligent persons are more or less concerned. The complex conditions resulting from numerous individuals living together have not here led to profound anatomical specialization, as they have in the case of such insects as ants.

SOCIAL FISHES (PISCES). That so many Fishes should be associated together in shoals would seem to be dependent in many instances on the place and manner of spawning. In ordinary bony fishes (Teleostei) the eggs are nearly always fertilized externally, and it is obvious that this process is facilitated when numerous individuals seek the same locality for the purpose. The Herring (Clupea harengus), fig. 1102), for example, approaches our shores in order to deposit its eggs in shallow water, where they adhere to various objects; the Salmon (Salmo salar) ascends rivers for the same purpose; and the Common Eel (Anguilla vulgaris) migrates in vast numbers to the deep sea in order to spawn. How far the movements of migratory fish involve division of labour is not at present known. It is not impossible that some of the older individuals may act as "leaders", though this is little more than a conjecture.

The gregarious habit of many predaceous fishes, such as Sharks, Dog-fishes, and Mackerel, may conduce to success in