COMPARATIVE COCOONING INDUSTRIES. 



167 



the point of attachment. The ahdomen was also swayed from cue side to 

 another, tlie filaments from the spinnerets following the motion as the 

 spider turned ; and thus an even thickness of silk was laid upon the eggs. 

 The same hehavior marked the spinning of the silken rug or cushion in 

 the middle of which the eggs had been deposited. It will thus be seen 

 that the entire process of forming a cocoon, as wrought by Lycosa, resem- 

 bles in every particular the mode practiced by Tubeweavers and substan- 

 tially by Orbweavers. 



So also is it with the Saltigrades. I have observed Phidippus rufus 

 spinning its cocoon, and she proceeds after the same general method. A Salti- , 



grade mother is represented at Fig. 20^, as sketched in the act 

 ^^^^^" of cocoon making. The diverging lin6s of silken spinning stuff 

 gra es. _^^^ \:\^qxq seen proceeding from the spinnerets, while the abdomen 

 is lifted up at a considerable incline, and the feet clasp the borders of the 

 cocoon. As this Phidippus revolved she alternately dropped and elevated 

 the abdomen, while the silken loops thus formed curled down into the 

 mass already spun and were further beaten in by the spinnerets and legs. 

 It thus appears from personal observation of typi- 

 cal species in all the tribes, with the exception of 

 the Laterigrades, that the manner of outputting 

 the spinning stuff while weaving cocoons is prac- 

 tically the same. The only difference observable 



is confined to the use of the spinnerets in beating fig. 2m. Phidippus rufus spin 



., , ,1 1 11 V, ■ nine her cocoon cover. 



down the outspun threads, these organs bemg 



more freely used for this purpose among the Tubeweavers and Tunnel- 

 weavers, who possess long pairs of superior spinnerets, than among others. 



III. 



Proceeding now to a comparative study of the cocooning industry of 



spiders, we observe, first, in view of the preceding sections of 



General ^j^j^ chapter, that the general method of spinning the cocoon, 



Method. ^^ ^* '^^^ \)G.Q\\ observed in representative species of all but one 



of the tribes, is substantially the same. 



1. That method consists in drawing out thickened lines from the spin- 

 nerets while the body is slowly revolved around the area to be occupied 

 by the cocoon; or, as in Theridium, the cocoon is revolved upon a sus- 

 pensory line. The loops thus drawn out are about the length of one-half 

 the distance between the surface points to which the cocoon is attached 

 and the point to which the spinnerets are raised by the elevation of the 

 abdomen. As the spinnerets drop after their elevation, the thread relaxes, 

 curls, and thus a soft loop of curled thread is left upon the growing 

 cocoon mass. In some cases this is beaten down b}' the feet and spinner- 

 ets, or spread over by them as a plasterer spreads mortar, until the cocoon 



