April 24, 1885.] 



KNOWLEDGE ♦ 



343 



dition, but has had its character so much altered as is 

 mvolTed in having passed several times through the hnnds 

 of the nianufactuivr ; thus, paper will furnish it with an 

 enjoyable meal, and books even yield it ;)/i//sica/ sustenance. 

 A curious case of the latter is recorded of eitlier this 

 insect or some closely-allied species ; twenty-seven folio 

 volumes in a public library were perforated in a straight 

 line by one and the same insect, and so regular was the 

 tunnel that a string could be passed through the whole 

 length of it, and the entire set of books lifted up at once 

 thereby — a tolerably clear proof that the library, or, at any 

 rat*, that particular portion of it, could not have been in 

 great request with human bookworms, or the insect ditto 

 would scarcely have found its course so entirely unimpeded. 



Drawings, and even paintings, have also been destroyed 

 by this insect, and on one occasion it invaded the sacred 

 seats of learning and made away with some Arabic manu- 

 scripts in a library at Cambridge, and at another time 

 wrought havoc in the herbarium of a botanist. The powerful 

 jaws of the larva, too, are not deterred even by a thin 

 coating of metal, for ^Vestwood records having seen tinfoil 

 jjerforated by it, no doubt for the purpose of pDfering some 

 treasure contained beneath. 



So, while A. domesticum destroys chairs, tables, picture- 

 frames, cupboards, floors, ic, and sometimes terrifies 

 nervous old ladies by its ticking, its relative A. paniceum 

 attacks the stores of comestibles, works of art, and litera- 

 ture of the dwelling, and between them they would, in the 

 course of time, if unchecked, produce terrible ruin. When 

 found in woodwork out of doors, the direct damage insects 

 of this kind do by the actual excavation and devouring of 

 the wood is not the only injury for which they are 

 responsible ; for damp air enters the substance of the wood 

 through the burrows, and meeting with the excrement 

 which is stored in great quantities in the burrows, renders 

 it a good basis for the growth of microscopic fungi, whereby 

 the decay of the wood is accelerated. 

 (To be continued.) 



THE 



EVOLUTION OF THE SENSE 

 OF BEAUTY. 

 By Constance C. W. Naden. 



(Continued from p. 309.) 



OUR inquiry into the origin of the love for brilliant 

 hues and varied contours receives a partial answer 

 from the obvious utility of the sense of colour, and still 

 more of the sense of form. Mr. Grant Allen shows that 

 the colour sense in insects has probably been developed in 

 connection with the flowers on which they feed, while that 

 of birds and of mammals has simDarly been developed in 

 connection with fruits, and that in both cases the faculty 

 thus evolved has been secondarily applied in the selection 

 of gaily-coloured partners. " If," he says, " the eyes of 

 insects were capable of distinguishing these bright colours, 

 in however imperfect a degree, it would naturally follow 

 that the hues would go on deepening from generation to 

 generation among the plants, while the perception would 

 go on sharpening itself from generation to generation 

 among the insects. For while the flowers which thus be- 

 come more and more readily distinguishaVjle by their 

 fertilisers would thereby better secure the chance of de- 

 scendants, the insects which most readily distinguished 

 flowers would thereby secure for themselves the greatest 

 amount of the available food-stores."* Similar reasoning 



* "The Colonr-sense : its Origin and Development," p. 40. 



may be applied in the case of birds which live on fruits and 



on resplendent insects, and the samo nerve-structure which 

 enables a bird or butterfly to discern the colour of its fooi\, 

 will, of course, enable it to discern the colour of its mate. 

 It is further shown that the most brilliantly-coloured 

 animals, as butterflies, ro.»e-beetles, humming-birds, barbets, 

 parrots, macaws, toucans, fruit-pigeons, frugivorous li?jirda 

 and quadruniana, are those which live on the most bril- 

 liantly-coloured food, while, conversely, carrion-feeders and 

 nocturnal and carnivorous animals are generally dull of 

 hue. 



But all this, as ^Mr. Allen points out, does not in any 

 way explain the loi-e of colour , neither, I may add, do the 

 very evident advantages of a clear discrimination of form 

 explain the love of special shapes.* 



We must leave the track which we have hitherto fol- 

 lowed, and look a little deeper for our explanation. It is 

 a well-known physiological fact that the normal — that is, 

 the natural and healthy — exercise of any function is 

 pleasurable. + It is naturally pleasant to the eye to look, 

 to the ear to hear ; except when the sights or sounds pre- 

 sented are in some way immediately harmful, and therefore 

 painful. Even were this not an induction, we might deduce 

 it from the theory of natural selection. An animal which 

 found its vital activities irksome would soon succumb to 

 more energetic congeners. To say that any being would 

 rather not see, or hear, or smell, or taste, or touch, or feel, 

 or think, is practically to say that it would rather not live, 

 and, consequently, that it would not be likely to take 

 very efficient measures to keep itself alive. The survivors, 

 then, will generally be those which not only have the 

 greatest fulness of life, but also the greatest enjoyment of 

 life ; and both endowments will usually be transmitted to 

 the offspring. Hence we may conclude that so long as 

 no direct pain, and no inherited or personal experience, 

 testifies against a sound or sight, it will be more or less 

 agreeable to a healthy organ. Till proved guilty, it is not 

 only innocent, but welcome. 



Since exercise is in itself a gratification, the amount of 

 gratification will, within certain limits, depend on the 

 amount of exercise, and therefore upon the strength of 

 the stimulus. These limits are reached when the organ 

 begins to feel fatigued ; that is, when it gives warning 

 that it is unable to do very much more work, and asks 

 for a holiday. This happens when the waste of tissue 

 exceeds the immediate repairing power. The greatest 

 pleasure is therefore derived from the maximum of activity 

 with the minimum of fatigue, j 



This depends upon two conditions. First, the stimuli 

 must be varied. They must appeal either to different 

 organs, or to different parts of the same organ, so that one 

 part may not suffer from weariness while another sutlers 

 from inertia. When one set of cells has for the time outr 

 worn its power of enjoyment, another set must be called 

 into play fresh from its sleep, exquisitively sensitive, and 

 eager to spend its accumulated energies. 



* Perhaps I may say that the next few paragraphs were written 

 before I had read Mr. Grant Allen's " Physiological yEstheticB," 

 and that, when I did read the book, I was pleased to find that I 

 had hit npon a similar line of argument, and, in one case, npon 

 nearly the same formula. 



t I do not except even the functions of those organs, or parts of 

 organs, which do not receive afferent fibres from the cerebro-spinaf 

 system. Normal secretions, digestion, circnlation, and respiration, 

 though not distinguishably pleasurable, unite to produce that state 

 of hien-aise known as good health ; which is, as it were, the back- 

 ground and matrix of all other pleasures. 



X Mr. Allen's formula is " the maximum of stimulation with the 

 minimum of fatigue." This, however, seems open to objection, 

 since activity and the consequent enjoyment do not always increase 

 directly with the stimulus. 



