304 DECEMBER. 



of the bag, which drives forward the globules contained 

 there; the contraction in an instant passes onward 

 along the three twists of the vessel, the part behind 

 expanding immediately as the movement passes on, and 

 the globules are forcibly expelled through the narrow 

 but open extremity. Meanwhile the free globules sur- 

 rounding the commencing end have rushed in as soon as 

 that part resumed its usual width, and are in their turn 

 driven forward by the periodic repetition of the pulsa- 

 tion. The fluid, with its globules thus put in motion, 

 is then driven along through the interstices of the various 

 organs of the body, not through a system of closed blood- 

 vessels, some finding their way along the transverse 

 lines that separate the rows of gill- ovals, until they 

 sooner or later arrive at the point where they entered 

 the heart, to take the same course over again. 



As in the kindred forms of animal life, the same 

 orifice, the same cilia, the same currents are subservient 

 to breathing and to the reception of food ; the stomach 

 digesting the microscopic animalcules which are poured 

 with the entering stream through the receiving siphon. 

 At some distance within the interior of this orifice 

 there are a series of thread-shaped tentacles, affixed in 

 a ring, which we may suppose to exercise some kind of 

 superintendence, by touch or other perception, over the 

 atoms which indiscriminately enter upon the stream, 



