INSECT. 



871 



syMem of muscles, some idea may be entertained, i 

 when it is stated that Lyonnet discovered 40(51 in ] 

 the caterpillar of the goat moth, 228 being attached ; 

 to the head, 1647 to the body, and 2186 to the intes- 

 tines ; whereas, in the human body, only 529 have 

 been discovered ; so that this insect possesses nearly 

 fight times as many muscles as there are contained in 

 the human frame. This, however, will not appear so 

 extraordinary, when the greater number of legs, &c., 

 in the insect are remembered. 



The construction of insect muscles is similar to 

 those of the higher animals, each being formed of 

 muscle and of tendon ; the former is fleshy, whilst 

 the latter, which forms the coating and extremities of 

 the muscle, is firm, and not liable to contraction. Ac- 

 cording to Lyonnet, the muscles are composed of 

 many parallel bands, consisting of bundles of fibres 

 enveloped in separate membranes ; these fibres ap- 

 pearing to be twisted in a spiral direction. These 

 muscles are attached at one end to the various pro- 

 cesses of internal surface of the outer covering, which 

 serves as their fulcrum, and the other end is attached 

 to the organ to be moved. The size of muscles is 

 proportioned to the movements to be performed by 

 i he organs to which they are attached: thus, the 

 muscles of the mandibles are much more robust than 

 those of the maxillae : in like manner the comparative 

 aize of the various organs influence that of the corre- 

 sponding muscles. Thus, when the anterior wing is 

 enlarged at the expense of the posterior, the ineso- 

 thoracic muscles are more developed than those of 

 the metathorax ; and vice versa, in like manner, the 

 muscles of the hind legs of a leaping insect, as a grass- 

 hopper, are more extensive than those of the simple 

 walking legs. Muscles, as regards their action, are 

 either flexors or extensors, levators or depressors : by 

 the flexors, which are attached to the inner surface of 

 a limb, it is drawn towards the base, and conse- 

 quently as it were folded up ; extensors, on the con- 

 trary, are attached on the exterior part of the cavity 

 of the outer covering of a limb, and acting in an 

 opposite direction, so as to extend the limb. In like 

 manner levator muscles cause the elevation of a limb, 

 whilst depressors bend it downwards. To describe 

 in a more particular manner the musc'es of insects, or 

 to trace their varied action in effecting the varied 

 motions which are exhibited by these animals, would 

 occupy a far greater space than we can by possibility 

 devote to the subject in this already too long article. 



4thly. The Physiological and Instinctive Properties 

 of Insects. 



Having brought to a close our review of the 

 general structure of insects, as exhibited not only in 

 their preparatory and perfect slates, but also in their 

 external and internal organisation, it would naturally 

 remain for us to lay before the reader the modes of 

 operation by which each of these various structures 

 is rendered serviceable towards the fulfilment of the 

 ends for which the insect has been produced. This 

 would comprise every physiological peculiarity pre- 

 sented to us by the insect world, independent of mere 

 structural modification. But in treating of the inter- 

 nal systems of organs, and, indeed, partially, in our 

 review of the external form of insects, we have 

 thought it might be more agreeable to the majority 

 of our readers to blend together effects with causes ; 

 operations with the apparatus whereby they are 

 effected. It still, however, remains for us, as pre- 

 viously observed, to notice the operations of that 



power, or principle, which seems totally independent; 

 of organisation, and to which the name of instinct is 

 generally applied. 



It is necessary for us, however, in the first place, 

 to premise, that it is not our intention to enter into 

 any disquisition upon the nature of instinct. We 

 know, indeed, nothing of the real nature thereof be- 

 yond what is exhibited to us by the various pheno- 

 mena of insect life, and which have been well 

 described as the result of a power " enabling an 

 animal to do that which, in those things that man 

 can do, results from a chain of reasoning ; and in 

 things which men cannot do, is not to be explained 

 by any efforts of the intellectual faculties *." 



Now these varied phenomena are manifested to us 

 in an endless variety of methods : in the affection of 

 insects for their offspring ; in the numerous distinct 

 modes in which the parent insect deposits her eggs 

 in the most appropriate situations; in the construc- 

 tion of nests ; in the various stratagems by which 

 insects procure their food ; in the modes of defence 

 employed by insects either against their ordinary 

 enemies or accidents ; but, more than all, in the 

 varied economy of social insects bees, humble bees, 

 wasps, ants, white ants. All these varied phenomena 

 appear, however, to be resolvable to two principal 

 heads the continuance of the species, and the pre- 

 servation of the individual : indeed, the great end and 

 final care of the endless labours of the social insects 

 can only be traced to one or the other of these causes. 



If we confine our attention to the first of these 

 grounds of inquiry, viz. the perpetuation of the species, 

 we find that here, as elsewhere, the great command 

 " Increase and multiply " is obeyed to the fullest ex- 

 tent, as is manifested by the various circumstances 

 connected with the pairing of insects, and especially 

 by the precautions which the parent female exhibits 

 in the careful deposition of her eggs, as already 

 noticed in the early part of this article ; whilst the 

 often extraordinary and always interesting peculiari- 

 ties exhibited by social insects in the construction of 

 their nests, for their own habitations and the rearing 

 of their offspring, the collecting of food, and the feed- 

 ing of young, have been treated upon in various other 

 articles of this work (ANT, BEE, FOKMICID^E, HUMBLE 



BEE, IcHNEUMONlD^E, &C.). 



If, on the other hand, we direct our attention to 

 the preservation of the individual (and many of the 

 peculiarities of social insect life conduct us to this 

 branch of our inquiry), we find the subject also divides 

 itself into two sections, namely, the various stratagems 

 employed for obtaining a supply of food, and the 

 means of active or passive defence adopted by insects. 

 With a few notices of some of the most remarkable 

 of each of these instinctive peculiarities, we shall 

 close the present branch of our subject. 



We have seen in the early part of this article that, 

 from the very nature of the functions of the insect 

 tribes, it is essential that the consumption by them of 

 animal and vegetable matter should uninterruptedly 

 be carried on. Hence, as well as from the nature of 

 insects in general, and the great care shown by the 

 female in depositing her eggs in the most fitting situ- 

 ations, there is but little occasion for any exhibition 

 of instinctive reasoning on the part of these animals, 

 with the exception of those which prey upon living 



Lieut. Col. Sykes, in Trans, of Entomol. Society, p. 106. 



