22 SPIDER GOSSIP. 



one only in the lengthwise section, Fig. i. It is obvious that, 

 when these muscles contract, the three plates separate, and a 

 passage is opened for the food. It then passes through the 

 stomach, and afterwards into the alimentary canal (in Fig. i). This 

 figure, as more perfect sections, cut since I drew it, have shown 

 me, is not perfectly accurate in its representation of the stomach 

 and intestine. The stomach is about as intricate in its contours 

 as a walnut in its shell, fitting in amongst the brain and muscles 

 as the walnut's kernel does amongst the surrounding tissues. It 

 has two entrances from the pharynx and one exit into the alimen- 

 tary canal. Only the exit is show'n in the figure. The entrances 

 lie one each side of the exit. The liver (Fig. i) is a collection of 

 branched tubes, surrounded by glands, which open into the 

 alimentary canal about where (in the figure) the muscles cross it. 

 This structure is not represented. 



One of the most conspicuous organs in Fig. i is the heart, ht. 

 It is hung, so to speak, down the middle of the upper part of the 

 abdomen, by ligaments, four of which are drawn. It is a long, 

 hollow vessel, composed of rings of muscles, and the blood gets 

 into it through little valves in the sides. Their position is cor- 

 rectly shown in the figure, but their shape is not exactly that of 

 the drawing. The blood is pumped through the body by the 

 contraction of these muscles, the wave of motion going from the 

 hinder end forwards. This circulation is worth looking at. 

 Choose a small insect with a transparent skin, and put it alive 

 under the microscope in a cell. You will then see the beating of 

 the heart, pulsations of the returning blood in the head-thorax, 

 and the course of the blood-cells in the legs and in what you may 

 call the " waist " — />., the part where the head-thorax joins the 

 abdomen. It is marvellous to see so plainly the generally hidden 

 movements of life. After being forced out of the heart, the 

 blood goes through the spider's waist by the main artery, which at 

 this point is swollen, and has what seems to be a flange-valve. 

 This artery goes over the pharynx, and, in the drawing, it is for 

 the sake of clearness made black and opaque. I rather think it 

 divides into two — an artery for each side of the body — just behind 

 the muscle which lifts the upper plate of the pharynx. Imme- 

 diately in front of the pharynx these vessels divide again (see 



