BATS. 



315 



they may not be disturbed in their repose (luring the 

 clay. The nostrils mid also the mouth are also some- 

 times surrounded by produced membranes, the use 

 of which is not very well knjwn. Perhaps they aid 

 the sense of smelling, which is generally acute in 

 nocturnal feeders ; perhaps they assist in the capture 

 of the insect prey ; and perhaps they arc in some 

 measure organs of touch. The eyes are very small 

 and deeply enfonced, something like the eyes of 

 moles ; and though they must have the power of 

 vision, it does not appear that they are essential to 

 the animal in finding its way, even when that is 

 intricate. The well-known experiments of Spallan- 

 zani, which were verified by others, proved that 

 when blindfolded, or even blinded, bats can find their 

 way through between obstacles of which they could 

 have had no previous knowledge ; and indeed though 

 we, reasoning' from ourselves as the example, are very 

 apt to suppose that what we call the caution of ani- 

 mals is a matter of experience, yet, prejudice and false 

 analogy apart, experience appears to have little or 

 nothing to do in the matter. Spallanzani suspended 

 willow rods in the room in which he turned the blind 

 bats loose to fly ; but, though he shifted these so as 

 to make the passage between them as varied and as 

 intricate as possible, the bats never struck against 

 one of them, though they kept flying about in all 

 directions. 



A question has hence been raised as to the means 

 by which bats do contrive to avoid obstacles ; and the 

 same question may be extended to very many other 

 animals. A horse in the dark pauses when he comes 

 to a closed gale, though he never was the road before; 

 nocturnal bivsts do not more frequently fall into pits 

 and over precipices, than beasts which are abroad 

 during the day and have their eyes to guide them : 

 and nocturnal birds do not fly against trees any more 

 than day-light birds. People, too, will keep a well- 

 known path though the night be pitch dark 



In the last case we are in the habit of saying, thai 

 " the feet know the road ;" and the saying is probably 

 not very wide of the truth. "Feet "or "head," we 

 know that which ivc have learned. Animals need no 

 learning in the performance of their natural functions 

 and therefore they know all ways instinctively which 

 their habits lead them to, and the nocturnal ones 

 luive no more difficulty in the dark than the diurna 

 ones have in the brightest sunshine: another proo 

 of the wisdom and goodness of the Creator. 



This, it will naturally be said, is not an answer to 

 the question ; but, though it would be easy enough 

 to write more, it is in truth all that can philosophically 

 he given. That the animals feel a different resistance 

 in the air in time to avoid the obstacle, the pit, or the 

 precipice, is evident ; but how they feel it, or even 

 what name we are to give it as a sense, is another 

 matter. Of sensation we have no knowledge beyonc 

 the experience of our own senses ; and what is sau 

 respecting them, even by those who are accountec 

 the "authorities" in matters of physiology, is vague 

 enough. The most rational theory on the subject is 

 that as the sentient animal is one, all the senses arc 

 ntially one also, only modified by different organs 

 And if modified by different organs in the same body 

 much more may they be modified by bodies which ar 

 specifically different, so that the sense which has appa 

 rently a similar organ, and to which (on that account 

 we give the same name, may be very different in twt 

 different animals. We are accustomed to say that 



lood-hound, which follows upon the " slot," has a very 

 xqnisite sense of smell ; but the hound cares nothing 

 or roses or mignonette, or all the perfumes in 

 he world ; and the eye of the eagle, much as has 

 >een descanted on its power of vision, has no percep- 

 ion of beauty either in forms or in colours. The 

 lying membranes of bats, thin as they are, contain a 

 jcautifuily reticulated plexus or net-work of nerves, 

 and the texture of them externally is of that descrip- 

 ion with which we usually associate a very delicate 

 sense of touch. But still we cannot say that such a 

 surface is absolutely necessary ; for it appears that 

 the whiskers of cats, the delicate fringes in which the 

 wing feathers of owls terminate, and many other 

 surfaces and substances in which there do not imme- 

 diately appear to be any nerves, give indications 

 qually delicate and certain. A blow on the horn of 

 an ox appears to pain the animal even more than a 

 similar blow on the hide ; and treading on the toe is 

 not a tittle the less painful for its being fortified by the 

 mail of a corn. 



Delicacy of sensation is rather a quality of the 

 general constitution of animals than of any local 

 organ ; and the bats appear to possess it in a very 

 high degree, not only as regards the contact of solid 

 substances or the mechanical motions of the atmo- 

 sphere, but as regards light and temperature. They 

 cannot bear wind, they come not abroad during 

 the day, and they hybernate in the winter. The 

 temperature which suits their nature appears to be 

 more limited than that of almost any other race of 

 animals. 



Their habits all tend to show this. They breed at 

 the very hottest time of the year ; and the young, 

 which are usually two in number, are naked and help- 

 less at their birth, capable only of clinging to the teats 

 of their mother, which, however, they do with the 

 greatest firmness and pertinacity. This habit in them 

 is necessary, for the mother does not lie down or even 

 stand on the ground when she suckles her young, as 

 is the case with most of the mammalia. She hangs 

 suspended, by the nails of her thumbs, or more gene- 

 rally by those of her hind feet, to the branch of a tree, 

 or some cranny or irregularity in a ruin. There is 

 no nest in which she can leave the young ones when 

 she goes out to feed ; and thus she must bear them 

 about attached to her body till they are capable of 

 flight. The female has no marsupium ; but this habit 

 resembles a little those of the marsupial animals 

 the young are very immature when produced ; and 

 their nest and place of safety and repose is the body 

 of their mother. 



Some of the species occasionally fly during the day, 

 but that habit is by no means common, and is con- 

 fined to some of the foreign species which are in part 

 vegetable feeders. In temperate climates, they conceal 

 themselves during the day, even in the season of their 

 greatest activity. Caverns, holes of trees and walls, 

 and ruined buildings are their retreats ; and from 

 these they issue forth as dusk begins to set in, flutter 

 about in their laborious flight, and capture such insects 

 as are then on the wing gnats, mosquitoes, moths, 

 and beetles; and their wide gape with its formidable 

 teeth is an excellent trap for the capture of such prey. 

 The service which they render to vegetation, by the 

 destruction of insects which in the larva state prey 

 upon it, is very considerable, even in temperate 

 climates ; and some of the hot countries in which 

 they swarm by myriads, could not, but for them, be 



