CHORD AT A, 155 



gill-slits, is collected, and passes into the same cloacal 

 chamber. The nervous system consists of a centre or 

 ganglion between the two openings, from which nerves 

 radiate to the various parts. There is a heart at the 



FIG. 73. Diagram of a Tunicate. Z), branchial chamber, perforated by 

 gill-clefts, and connecting at the bottom with the oesophagus which leads 

 to the globular stomach, and thence by the intestine to the vent, v ; h, 

 heart ; n, nervous system ; m, mouth. 



opposite side of the body, and a peculiarity of this organ 

 is that it regularly changes in its action, the blood flowing 

 in a direction opposite to that which it followed a moment 

 before. 



The species of Tunicates are numerous, and show great 

 variety of form. A characteristic of many is the power to 

 reproduce by budding, and as a result there are formed 



