CRUSTACEOLOGY. 



419 



the 9pider leapt inte die air, and the thread mounted 

 her up swiftly. He afterwards made the same obser- 

 vation on about thirty other species of spiders, and 

 found the air filled with young and old sailing on their 

 threads, and probably seizing insects in their passage, 

 as he found legs and wings, and other manifest signs 

 of slaughter, on those threads, as well as in the webs 

 below. These observations were corroborated by Dr 

 Hulse, who made the like discovery about the same 

 time. It is Dr Lister's opinion, that this darting of 

 threads was known to Aristotle and Pliny, (vide Aris- 

 totle, Historia Animalium, lib. ix. cap. 89. and Plinius, 

 lib. x. cap. 74.) ; but believes their sailing was first 

 observed by himself. On these sailing spiders he farther 

 observes, that they will often dart not a single thread 

 alone, but a whole sheaf at once, consisting of many 

 filaments, all of one length, but divided from each other 

 and distinct ; and the longer they become, the more 

 they spread, and appear like the numerous rays of a 

 blazing star. He observed, too, that some species 

 seemed to use their legs as oars, sometimes closing, 

 and again spreading them out, as occasion might re- 

 quire. When the air is still, it is highly probable they 

 can direct their course, and perhaps mount or descend 

 at pleasure. In rowing, he observed they always take 

 their flight backwards. These threads mount to an al- 

 most incredible height, and may always be observed in 

 a fine clear day in autumn, when there is little or no 

 wind. In a letter to Mr Ray, he farther observes, 

 " that I one da) r observing the air full of webs, forth- 

 with mounted to the top of the highest steeple on the 

 minster (at York), and could there discern them ex- 

 ceedingly high above me." Thus have we briefly sta- 

 ted the observations of this celebrated naturalist, to 

 which we may add his conclusions : They mount their 

 threads upwards, and mount them in a line almost per- 

 pendicularly. This is not all ; they also project them 

 in a line parallel with the horizon, as may be seen by 

 their threads running from one wall to another in a 

 house, or from one tree to another in a field or garden. 

 By what power this is done he does not attempt to 

 show : It only, as he observes, " magnifies our ideas 

 of that Being, who has given to so apparently con- 

 temptible an animal such vast powers for its mainte- 

 nance and pleasure." 



The apertures from which the web is produced are, 

 according to Reaumur, very numerous. He says there 

 are, in the compass of a pin's head, enough to yield an 

 amazing number of distinct threads. These holes are 

 perceived by their effects : Take a garden spider ready 

 to deposit its eggs, and apply the finger to one of the 

 papillae or teats, and as you withdraw your finger, a 

 vast many distinct threads will appear. Reaumur has 

 often counted seventy or eighty by the assistance of a 

 microscope ; and perceived a vast many which he could 

 not distinctly count. He says, that were he to say 

 each teat has a thousand apertures, he should say too 

 little. Each nipple is covered with minute promi- 

 nences, and each of these probably has a vast number 

 of openings ; or between its several protuberances are 

 holes, which give vent to threads : The use of these pro- 

 minences may be to keep the threads asunder, at their 

 first exit, before they are hardened by the air ; and this 

 is rendered very probable, as some spiders are provi- 

 ded with tufts of hair instead, which may serve the 

 purpose of keeping the threads at a proper distance 

 from one another. Leeuwenhoek has computed, that 

 ene hundred threads of a tolerably sized spider are not 



equal to the diameter of the hair of a man's beard, and, 

 consequently, if the threads and hair be both round, 

 ten thousand such threads are not larger than such a 

 hair. And as young spiders (which are not, when first 

 hatched, altogether as large as a single papillae of the 

 mother which produced them,) spin as soon as they 

 quit the egg, he farther calculates, that as four hun- 

 dred young ones are not larger than one full grown, 

 four millions of their threads are not so thick as a hair 

 of a man's beard. Some experiments have been made 

 to manufacture the threads of spiders into silk ; these 

 we shall detail when their natural history is concluded. 

 The use of the webs above described, seems to be 

 principally for the purpose of taking their prey, and 

 defending them from the attacks of birds, some kind* 

 constructing strong webs for that purpose. Their food, 

 in every stage of their existence, consists of insects ; 

 nor do they spare their own species, preying on one 

 another witli the most savage ferocity. These inherent 

 qualities create a disgust which even the expansion of 

 philosophy will not always suppress. Thomson prc~« 

 bably felt this sympathy of the mind, in his descrip- 

 tion of the spider ; „ 



To heedless flies the window proves 



A constant death ; where gloomily retired, 



The villain spider lives, cunning and fierce. 



Mixture abhorred ! amid a mangled heap- 



Of carcases, in eager watch he sits, 



O'er-looking all his waving snares around. 



Near the dire cell, the dreadless wanderer oft 



Passes, as oft the ruffian shews his front ; 



The prey at length ensnared, he dreadful dart* 



With rapid glide along the leaning line ; 



And fixing in the wretch his cruel fangs, 



Strikes backwards grimly pleased; the flutt'ring wingv 



And shriller sound, declare extreme distress, 



And ask the helping hospitable hand." 



The weapons with which they seize their prey, is * 

 pair or sharp crooked claws or forceps placed in the 

 front of the body. These they can open as occasion 

 may require ; when at rest, they lie one over the other. 

 Leeuwenhoek says, that each of these claws has a small 

 slit or aperture, through which a poisonous juice is in- 

 jected into the wound they inflict. Dr Mead, in his 

 Essay on Poisons, dissents from this altogether, having 

 never been able, on repeated examinations, to discover 

 any such opening, not even in the claws of the largest 

 species. We have likewise investigated this point, and 

 find that in many species there is a groove ; but we are 

 very confident it is nothing more, never having been 

 able to discover any opening in the groove, after re- 

 peated examinations. Dr Mead says, that a small pro- 

 boscis is thrust out of the mouth at the time the spi- 

 der inflicts the wound, and infuses poison into it. Whe- 

 ther this be correct or not we shall not pretend to say, 

 never having examined any of the large exotic species 

 in a recent state ; in our own species, nothing of the 

 sort has hitherto occurred. 



The part of generation of the male spider resides at 

 the extremities of the palpi, which open, as it were, 

 with a spring during the act of copulation ; those 

 of the female are situated under the abdomen. As 

 these animals prey on each other except during the 

 time of their amours, they dare not come within reach 

 of one another but with the utmost caution. Some 

 species may be observed, stretching out their Jegs, 

 snaking the web, and tampering with one another by 

 a slight touch with the extremity of their feet; then i» 



