The chief use of the silk spun from the aciniform glands, in 

 the case of the orb-weaving spiders at least, is the production 

 of what may be termed the swathing band, the band of silk 

 with which these spiders envelop their prey. The act of swathing 

 can be easily observed by throwing a large insect into the web 

 of one of the larger of the orb-weaving spiders. The spider 

 first rushes at the insect and pierces it with the claws of its 

 chelicerie, and then darts back into a position of safety. This 

 may be repeated several times ; or, if the spider is not afraid 

 of its victim, the biting may be omitted. Then the spider ap- 

 proaches the insect and, pulling out a sheet of silk from its spin- 

 nerets, with one hind leg thrusts the sheet against the insect. 

 In doing this the spider uses first one hind leg and then the 

 other. In the case of the larger spiders this sheet of silk is 

 sometimes an inch in length, the body of the spider being held 

 that far from the insect ; under these conditions the sheet can 

 be seen to be composed of a very large number of parallel threads. 

 As soon as the sheet is fastened to the insect the spider rolls the 

 insect over and over and thus wraps it in its shroud. 



I have observed the making of the swathing band many 

 times, but owing to the timidity of the spiders observed, I have 

 never been able to determine to my complete satisfaction whether 

 the silk comes from all of the spinnerets or only from the 

 hind and middle ones. If it comes from only the hind and 

 middle spinnerets it is the product of the aciniform glands 

 alone, but if it comes from all of the spinnerets, which it 

 appears to do, it is the product of both the aciniform and 

 pyriform glands. 



In addition to the attachment disks and the swathing bands, 

 there are other structures that are evidently spun from the 

 small spinning tubes, and are consequently the product of either 

 the pyriform or the aciniform glands, or of both. Among these 

 may be mentioned the stabilimentum, the zigzag ribbon of silk 

 which some orb-weavers spin across the centre or below the hub 

 of their webs. Fig. 2 represents the more common type of 

 stabilimentum, and shows well that it is composed of many fine 

 threads. The young of Metargiope spin a much more elaborate 

 stabilimentum, which is lacelike in form (PL III, fig. 3). 



Many spiders build retreats which are evidently formed of 



