SPIDERS, MITES, AND SCORPIONS. 



161 



numbers of little two-jointed tubes, each the outlet of a silk-gland. The 

 silk, as secreted by the glands, is fluid, but after it comes to the air ii 

 rapidly hardens. The spider has full con- 

 trol of its silk supply and its spinning-tubes. 

 If it wishes, it keeps its spinnerets all sep- 

 arate, and then the product is numbers of 

 distinct threads. If it brings the spinnerets 

 together, the various threads unite as they 

 are formed into what is often called a cable, 

 but which is really one larger thread, and 

 not a cable at all. When a thread is to be 

 ! leguri, the spicier presses its abdomen against 

 some object, and thus fastens one end, and 

 then proceeds to draw out the rest ; at other 

 times, as when she wishes to pinion a fly, 

 the thread is pulled out with the feet. The 

 spider can even force out the thread without 

 any such external aid, as is seen when they 

 wish to ' fly.' Frequently one will see young 

 spiders in autumn mounting to the tops of 

 the pickets of the fences, and then elevate 

 their abdomen until it points almost directly 

 upward. Now a thread or a bundle of threads 

 is forced out which catches the breeze, and 

 is drawn out to such an extent that it buoys 

 up the spider, which then looses his hold 

 and goes sailing away. On some of the fine days in autumn hundreds 

 of these flying spiders may be seen, but what their object is in trav- 

 eling in this manner it is difficult to say. It may be that it is wholly for 

 the pleasure of travel, but this is doubtful. Among the lower forms of 

 animals, so far as we know, every act has some utilitarian end ; nothing 

 seems to have enjoyment for its sole object. 



The cobwebs are the product of comparatively few species, but they 

 differ so in their character that a study of them is very interesting. Som<- 

 of them are horizontal, others nearly vertical ; but even those which seem 

 upright will be seen on more careful examination to incline a little from 

 the perpendicular, and in all the spider walks not on the upper, but on 

 the under side : indeed, some spiders are so constructed that they can 

 hardly Avalk upright, while the claws of their feet are admirably adapted 

 for supporting the weight of the spider in a hanging position. Some 

 spiders, like the common house-spider, form irregular webs, the threads 



Fig. 142. — Nest of Lycosa. 



