184 THE ORGANIZATION 



of similar bodies so disposed within it that one group trends 

 along its lower central line, and the others are arranged right 

 and left, two on one side and two on the other. Let us see now 

 of what these groups consist. In the centre is the mouth, (fig. 

 Ill,) which is a simple round aperture, that leads, through a short 

 throat, into a broad stomach (st), which may be described as 

 having five sides, namely, one on the abdominal, or lower line 

 of the tube, which corresponds to one of the arms of the star- 

 fish, and two on each side at equal distances apart, opposite the 

 other four arms. From the five corners of this organ five pairs 

 of deeply folded and puckered sacs (st l ) stretch out into the arms, 

 nearly to their tips. Each pair is divided between two adjacent 

 arms, so that every two of each arm belong to different pairs. 

 From the mouth into the stomach, and thence to the ends of 

 the ten plicated sacs (st l ) is one unbroken communication, the 

 whole expanse of which is devoted to digestion of food ; the 

 saccules performing the part, it is thought, which corresponds to 

 what is called in the higher animals chylification ; a process 

 which usually succeeds the first rough preparation by which 

 the particles of food are reduced to a semifluid state. 



At a short distance behind the mouth the throat is encircled 

 by two rings, (aq, n,) of which the larger one (ri) is nearest the 

 eye, as we now survey the organization. From the latter, which 

 is looked upon as a nervous collar, five equidistant nervous 

 threads (w 1 , n 2 } extend along the middle line of each arm, and, as 

 they pass, give off, in opposite pairs, numerous minute side- 

 branches to the neighboring organs, and especially to the double 

 rows of tube -like feet (see fig. 110) which project through a 

 series of pores along the front face of each arm. 



In like manner from the smaller ring, (aq,) which is hollow, 

 five equidistant, thin tubes (aq l , aq 2 ) arise, and run along the 

 middle of each arm ; but as each immediately underlies a nervous 

 thread, the lower median nerve and the next one on its right 

 are left out of the illustration in order to expose some of them 

 in this figure. These tubules also give off opposite pairs of 

 branches, which penetrate the tube-like feet that I just mentioned. 



