Superfamily Argiop&L-a 



successive turns of the spiral showing that the spider passed back 

 and forth, in making it. 



This notched nature of the spiral is doubtless correlated with 

 the fact that the spiral is to remain a permanent part of the web, 

 and is made of dry and inelastic silk as is the case with the few 

 turns of the spiral guy-line constituting the notched zone of an 

 ordinary orb-web. 



As the turns of the viscid lines are spun in the spaces between 

 the turns of the guy-line it results that the viscid threads are in 

 groups as shown in Fig. 441. 



The viscid silk and the dry silk differ in colour, the former 

 being yellow, the latter white. The viscid drops are frequently 

 so large that they can be easily seen with the unaided eye. Ac- 

 cording to Doctor Wilder ('66) the yellow silk is spun from the 

 fore spinnerets. 



In the case of old spiders where the abdomen is filled with 

 eggs and movement is consequently more laborious, the spider 

 repairs only one half of the web each day. Figure 442 represents 

 a web, one half of which was repaired the night before the picture 

 was taken. The spider that made this web was under observation 

 for a considerable time and it was found that each night she re- 

 built one half of the web. During the period that this spider 

 was under observation there was a very severe storm, five inches 

 of rain falling in the course of a few hours. When the web war 

 visited on the following morning it was found that it had been 

 repaired throughout. (Fig. 439.) In repairing the web this 

 large spider walked sideways with her head directed upward 

 and her legs extending over two or three turns of the spiral guy- 

 line. As stated above, the web is slightly inclined and the spider 

 hangs throughout the day from the lower side of the hub. 



The silk of the spiders of the genus Nephila surpasses in 

 strength and in beauty that of the silkworm; and it is being util- 

 ized to some extent. The more important of the investigations 

 which demonstrated the practicability of using this silk were 

 the following: those made in this country by Prof. Burt G. 

 Wilder, with Nephila davipes; those by Pere Camboni, a French 

 Roman Catholic missionary in Madagascar, with Nephila mada- 

 gascanensis; and those by some Chinese at Yun-Nun. with 

 Nephila clavata. 



Professor Wilder published an account of his experiments 



* 



43> 



