Page:The New International Encyclopædia 1st ed. v. 10.djvu/748

* INSECT. 660 INSECT. the caste is already determined in the insect before leaving the egg; Weism^nn apsociates the cas>te with some hypothetical rudiments existing at the very earliest stage of the embryonic pro- cess; Herliert Spencer and ethers believe that the character of the insect is determined ty the nutri- tion of the larva, just as is the case with the honey-bee. The chief forms of polymorphism in antsare the ordinaiy winged male, the ergaloid male, the winged female, the ergatoid fertile female (a form intermediate between female and worker ). the soldier, the worker major, and one or more kinds of worker minor, in addition to these there are apparently cases of females with post- metamorphic growth in the Dorylides, bnt these have not yet been the subject of investigation. The fact that the social insects in which the phe- nomena of caste or polymorphism occur, though belonging to very dillerent groups, all feed their young, is suggestive and lends weight to the theory that the din'erenliation is the result of character of the larval food. Emerj' account.? for this differentiation by assuming that it has been gradually acquired by numerous species and that we now see it in various stages of development ; also, according to Sharp, "that the variation in nutrition does not affect all the parts of the body equally, but may be such as to carry on the development of certain portions of the organiza- tion while that of other parts is arrested." The so-called intelligence of bees, and especially of ants, has i)een a subject of wonder and com- ment on the part of many writers for lumdreds of years. The observations of Lubbock, however, indicate that bees have not the high degree of intelligence with which many writers have credited them, and that in this respect they do not compare with the higher ants, which are ranked as the highest in point of intelligence among social insects. Riley, in his work entitled Sticial Insects from the Psiichient and Krnlu- iional I'oinis of View, expressed him.self as of the opinion that no one can doubt the possession by the social insects of intelligence, of conscious reasoning and reflective powers. He makes the statement, "We can never properly appreciate nor properly bring ourselves into sympathy with these lower creatures iintil we recognize that they are actuated by the same kind of intelligence as ours." Bethe (ISilS), however, in discussing the question as to whether or not we may ascribe psychical qualities to ants and bees, points out the danger of the observer injecting his own per- sonality into the subject investigated. He shows, for exam])le, that while we see. all we know about bees and ants is that they are influenced by the light, and that it would be most unscien- tific to say that they do an.-thing as highly psychical as seeing, imtil it is proved. Some of the peculiar and apparently highly intelligent things which ants do. such as recognizing the enormous number of members of the same colony, and such as finding their way to their own nests and to food-supplies and communicating intelli- gence of the location of food-supplies from one to the other, have been carefully tested by Bethe, who concludes that he can find nothing in the phenomena exhibited by bees and ants to prove the existence of any psychical qualities. Lub- bock thought that he had proved that ants com- municated with one another, but Bethe ised one of Lubbock's own experiments to show that it proved nothing. He concludes that they learn nothing, but act mechanically in whatever they do, "their complicated reflexes being set off by simple physiological stimuli." See facts under this head in article Instinct. In the termites or 'white ants' we reach a very specialized form of the social or conununity life of insects. Thej- reach their highest development in tropical regions; the females or queens grow ti> be of enormous size, the abdomen swollen with eggs sometimes becoming as big as a potato, or twenty thousand or thirty thousand times the hulk of a worker. The eggs may be laid at the rate of GO a minute or 80,000 a day. The species arc all .social, and communities consist of both wingless and winged individuals. The winged individuals are with most species excessively nu- luerous, and as a rule they are divided into two castes, namely the ordinary workers and the soldiers. The so-called soldiers also exist with the true ants, but they have not in these crea- tures become such a structurally welldifferen- tiated caste as with the termites. In the latter the jaws have become enormously developed, and in some cases the soldier is five times the size of the worker. In some species some of the workers have branched off into another caste, the 'nasuti,' in which the head has become elongated into a long nose-like process, at the tip of which is a hole through which is exuded a fluid whieh is used in making and mending the walls of the habitation. Although the social life of a termite colony is .superficially much like that of an ant colony, the development of the social habit and the dif- ferentiation of forms have taken place along en- tirely different lines: the termites have an in- complete metamorphosis; the ants have a complete metamorphosis ; the young of the ter- mite is more or less capable of self-support soon after birth, whereas the larva- of the bees and ants are entirely helpless during developnient, and are fed by the adults. The fundamental dif- ference between the two groups is that with the termites the workers or neuters, including the soldiers, are not undeveloped females, as with the workers and soldiers of the ants, and the workers of the bees, but they consist of both sexes and are in reality the arrested or nicdified larvic in which the sexual organs are imperfectly developed or are completely atrophied. With the hive-bee, multiplication of colonies takes ])lace by division, but the cohmizing swarm carries with it a queen, and thus the foundation of a new colony is easy. With the higher ter- mites multiplication of colonics also takes place by division, but this is carried out by the workers and soldiers which travel away and capture one of the royal pairs that wander about after they have swarmed and thrown off their wings. ^lany colonies of termites will be found in which there is no queen. Among the different species of ter- mites there is a marked gradation from a simple to a more complex economy. The continuance of a termite community is entirely dependent upon the king and queen, which are the adult indi- viduals of both sexes which have swarmed and lost their wings. There is usually but a single pair in a nest, and they are frequently inclosed in a cell which they cannot leave. In consequence of the disorganization of the community if any- thing happens to the king or queen, termites keep certain individuals in reserve in such a state of advancement that they can rapidly be developed into kings and queens should occasion require it.