$d T|IE VITAL FUNCTIONS. 



tuting 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 further 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 



* Journal de Physique, Ixxxix, 146. 



