112 SPIDERS [CH. 



Though Epeira has some 600 silk-glands, it has 

 only five different kinds of gland, manufacturing silk 

 of different properties. No other family of spiders 

 has so many, though two other kinds of gland have 

 been found in less elaborate spinners. Within the 

 spider the silk is fluid but it solidifies on meeting the 

 air, each thread hardening as it emerges though 

 still continuous with the fluid contents of the gland, 

 so that the drawing out of a silken thread is just like 

 the operation so familiar with the glue-pot, or with 

 spun glass, except that the hardening is not due to 

 cooling but to exposure to the air. This general 

 description will, it is hoped, make an account of the 

 organs in Epeira more comprehensible. 



The spinnerets of Epeira are so small and incon- 

 spicuous that their disposition is not very easy to 

 make out. When not in use they form a tiny cone 

 under the tip of the abdomen, and only four are 

 visible, their free ends being so brought together as 

 entirely to conceal a small central pair. There are 

 really, then, three pairs of spinnerets which we may 

 call at once the anterior, median and posterior pairs, 

 though when at rest only the anteriors and posteriors 

 can be seen. If the spider is observed with a pocket- 

 lens as it crawls about in a glass tube it will be 

 noticed that the spinnerets are capable of great 

 mobility. Their ends can be separated or brought 

 together, or they may be made to rub against each 



