24 



SPIDER GOSSIP. 



each side of the abdomen, and, after considerable pains, I have 

 arrived at a tolerably complete idea of their structure and func- 

 tion. Fig. 2 gives a lengthwise section of one. The magnifying 

 power is twice as great as in Fig. i, but its place in Fig. i would 

 be — if the section were cut more to one side — exactly where the 

 ovipositor is. In a section cut lengthwise, as in Fig. 2, the gills 

 of a garden-spider appear to consist of about forty very thin 

 pockets or loose leaflets. Only twenty-two are drawn in the 

 figure, because, in the space that ought to contain forty, I could 

 not draw them thin enough. Fig. 3 gives the edges of three of 

 them very highly magnified. A comparison of these two figures 

 will show that the " leaflets " are double — the blood circulates 

 inside them. They are thick enough, and no more, to allow one 



-?^>6' 



■lar^di 



Fig. 6. — Cross section of Head-thorax of Spider, cut through 

 at the place where a line would join the letters br. 

 and p.g. in Fig. 1. Magnified ten diameters. 



layer of blood cells to pass freely. The upper surfaces are seen 

 to be (in Fig. 3) covered with very fine bristles. These bristles 

 keep the leaflets apart, so that air passes between them. Thus, in 

 a spider's gills there are forty layers of blood and forty of air. 

 Manifestly a very large quantity of blood is exposed to the freshen- 

 ing influence of air in a very short time, and although it may not 

 really be more wonderful than many other structures, the singular 

 aptness of this contrivance seems to me to bring before us the 

 wisdom of the Creator in a most striking way. The appearance 

 of Fig. 2 is rather deceptive. It is not so much that there are 

 forty leaflets containing blood, with air between each leaflet, as 

 forty leaflets containing air, between and across which blood flows 



