24:4: EVENINGS AT THE MICROSCOPE. 



a softer and more silken kind of web is prepared for 

 the purpose of receiving the eggs, and to serve as a 

 nest for the young." * 



The silk with which these various fabrics are con- 

 structed is a thick, viscous, transparent liquid, much 

 like a sohition of gum arable, ■which hardens quickly 

 on exposure to the air, but can meanwhile be drawn 

 out into thread. So far, it agrees with the silk of the 

 silkworm and other caterpillars ; but the apparatus by 

 which it is secreted, and that by which it is spun, are 

 both far more complex and elaborate than those of the 

 latter. Generally speaking, there are three pairs of 

 spinnerets, or external organs, through which the 

 threads are produced, but in some few cases there are 

 only two pairs, and in others, as the Garden Spiders 

 {Epcira)^ the hindmost pair seem to be united into a 

 single spinneret. These are always situated at the 

 hinder extremity of the body, and I will show them to 

 you presently. First, however, I will describe the in- 

 ternal apparatus — the source of the threads. 



The glands which secrete the gummy fluid are 

 placed in the midst of the abdominal viscera, and in 

 some instances — as in the female of Epcira fasciata, 

 a species which makes a remarkably large web — they 

 occupy about a quarter of the whole bulk of the ab- 

 domen. About five diflerent kinds of these glands 

 may be distinguished, though they are not all present 

 in every species. The Epeirce^ however, present them 

 all. 



In this genus there are : — 1. Small, pear-shaped 

 L«ags, associated in groups of hundreds, and leading oft* 

 by short tubes, which are interlaced in a screw-like 



* Comp. Anat. (Ed. 2), p. 458. 



