86 THE VITAL FUNCTIONS. 



tilting four stomachs, joined at a common centre. 

 Such, indeed, is the actual structure in the 

 Medusa aurita, in which Gaede found the 

 stomach to consist of four spherical sacs, com- 

 pletely separated by partitions. These arched 

 cavities, or sacs, taper as they radiate towards 

 the circumference, and are continued into a 

 canal, from which a great number of other 

 canals proceed, generally at first by successive 

 bifurcations of the larger trunks, but afterwards 

 branching off more irregularly, and again uniting 

 by lateral communications so as to compose a 

 complicated net- work of vessels. These rami- 

 fications at length unite to form an annular 

 vessel, which encircles the margin of the disk. 

 It appears also, from the observations of Gaede, 

 that a farther communication is established 

 between this latter vessel, and others which 

 permeate the slender filaments, or tentacula, that 

 hang like a fringe all round the edge of the 

 disk, and which, in the living animal, are in 

 perpetual motion. It is supposed that the elon- 

 gations and contractions of these filaments are 

 effected by the injection or recession of the 

 fluids contained in those vessels.* Here, then, 

 we see not only a more complex stomach, but 

 also the commencement of a vascular system, 

 taking its rise from that cavity, and calculated to 



* Journal de Physique, Ixxxix, 146. 



