A SPIDER 27 
The digestive system consists of a straight alimentary tube and 
its many branches. In the cephalothorax, branches of it extend 
to the legs, and a portion of it forms a sucking stomach, by 
means of which the spider sucks up its fluid food. In the abdo- 
men it becomes the intestine and gives off an extensive network 
of tubules, which fills a large part of the abdomen and has the 
appearance of a compact gland; its function, however, is not 
secretory and it does not differ in structure from the rest of 
the intestine. The end intestine possesses a large dorsal fecal 
reservoir. 
The kidneys are a pair of branching Malpighian tubules. 
The brain lies just beneath the eyes. It is joined, by means of 
broad connectives, with the large ventral ganglionic mass, from 
which nerves extend into the abdomen and the appendages. 
The organs of respiration are the lungs and the trachee. The 
lungs are a pair of sacs which open to the outside through the 
lung spiracles, each sac containing a series of lamelle, usually 
called a lung-book, in which the blood circulates. The trachee 
open to the outside through the tracheal spiracle. 
The sexes are separate in spiders. In the male the testes are 
a pair of tubular glands which are joined, by means of the coiled 
sperm ducts, with the sperm vesicle, which opens to the outside 
through the genital pore. The ovaries, in the female, are large 
organs in the ventral portion of the abdomen, which are joined, 
by means of the oviducts, with the uterus, which, after receiving 
the paired receptacula seminis, opens to the outside through the 
genital pore. 
The siik glands are branched or tubular structures in the 
ventral portion of the abdomen. 
