116 SPIDERS [CH. 



rather finer than those from the anterior, but 

 composed of the same kind of silk. 



There remain seven pairs of spigots whose function 

 has still to be explained, two on the middle and five 

 on the posterior spinnerets. The three which are 

 clustered together on the posterior spinneret do not 

 form silk at all, that is, the material they emit does 

 not harden on exposure to the air but remains fluid 

 and adhesive. When the spider is spinning the 

 "viscid spiral' of its web it is from these spigots 

 that the sticky matter oozes, enveloping the true 

 silken lines and presently resolving itself into little 

 globules in the manner already described. 



The remaining spigots two on the middle and 

 two on the posterior spinnerets are employed only in 

 spinning the egg-cocoon, and the silk they produce 

 is unlike that used in making the snare, being much 

 stronger and less elastic, and in the case of the 

 garden-spider of a yellow colour. In the occasional 

 attempts which have been made to substitute spiders 

 for silkworms as commercial silk producers, it is only 

 this cocoon silk that has given any considerable 

 results, the produce of the other glands being far too 

 frail for profitable use. Such attempts, however, 

 have always failed, principally for a reason quite 

 unconnected with the particular nature of the silk, 

 namely, the difficulty of keeping the spiders in 

 captivity. It is a simple matter to supply dozens of 



