SPIDER GOSSIP. 19 



power in No. 3 is so much greater, I have marked four thousandths 

 of an inch magnified to the same scale, to help the uninitiated to 

 estimate the minuteness of the object. 



The poison glands are like two little sausages ; but they are 

 hollow bags, containing fluid poison, and if one be crushed on 

 blue litmus paper, the poison will escape and redden the paper. 

 Thus we see that the poison is an acid — formic acid, I believe. 

 Their sides are double, consisting of an inner skin of " epithelial " 

 cells, which strain the elements of the poison out of the blood; 

 and an outer skin of muscular fibres. This is well shown in the 

 cross section. Fig. 6, and the spiral arrangement of the muscular 

 fibres can be seen both in this drawing and in Fig. i. The 

 tightening of these fibres by contraction forces out the poison in 

 front, just as the wringing of a wet cloth squeezes out the water at 

 the sides. It goes, as Fig. i shows, down a long thin tube, through 

 the jaw and fang, and is ejected from the latter through a tiny 

 hole, a little space behind its point. This hole is too minute to 

 be shown in drawings on such a small scale as Figures i and 4. 



What a truly formidable weapon (to a fly) is a spider's jaw — 

 even without the poison ! Its solid basal joint is moved by 

 powerful muscles situate in the head-thorax. A part of one 

 muscle only is drawn in Fig. i, because the others do not lie 

 within the plane of the section. Then there is the keenly-pointed 

 fang, sharper than the finest needle. This can be best seen in 

 Fig. 4. In Fig. i the jaw is not drawn in section, like the rest of 

 the figure, but in perspective, because I wished to show the tube 

 connecting poison gland and fang, and this, like the muscles 

 aforesaid, does not lie in the plane of the section. The fang is 

 moved by muscles lying within the basal joint. The spider 

 catches its prey by the leg or body ; gives it an awful pinch ; the 

 sharp fangs go through the skin ; and the poison is forced into the 

 wound. Poor little fly ! It is soon dead, and then its blood is 

 sucked. 



Now, this process is exceedingly curious. Underneath its 

 fly-catching jaws, a spider has another pair, which, with" the two 

 lips, constitute its fly-sucking apparatus. • They are shown in 

 perspective, viewed from beneath, in Fig. 4, which also shows the 

 under lip in the middle of the drawing. The two lips are drawn 



