NUTRITION IN POLYPI. 63 



monsters more complicated than the wildest fancy has con- 

 ceived. 



Still more complicated are the forms and economy of those 

 many-headed monsters, which prolific nature has spread in 

 countless multitudes over the rocky shores of the ocean, in 

 every part of the globe. These aggregated polypi grow in 

 imitation of plants, from a common stem, with widely ex- 

 tended flowering branches. Myriads of mouths open upon 

 the surface of the animated mass; each mouth being sur- 

 rounded with one or more circular rows of tentacula, which 

 are extended to catch their prey: but as the stationary con- 

 dition of these polypes prevents them from moving in search 

 of food, their tentacula are generally furnished with a mul- 

 titude of cilia, which, by their incessant vibrations, deter- 

 mine currents of water to flow towards the mouth, carrying 

 with them the floating animalcules on which the entire po- 

 lypus subsists. 



Each mouth leads into a separate stomach: whence the 

 food, after its digestion, passes into several channels, gene- 

 rally five in number, which proceed in different directions 

 from the cavity of each stomach, dividing it into many 

 branches, and being distributed over all the surrounding por- 

 tions of the flesh. These branches communicate with simi- 

 lar channels proceeding from the neighbouring stomachs: so 

 that the food which has been taken in by one of the mouths, 

 contributes to the general nourishment of the whole mass 

 of aggregated polypi. Cuvier discovered this structure in 

 the Veretilla, which belongs to this order of polypi: he also 

 found it in the Pennalula, and it is probably similar in all 

 the others. Fig. 246 represents three of the polypes of the 

 Veretilla, with their communicating vessels seen below. 

 The prevailing opinion among naturalists is, that each poly- 

 pus is an individual animal, associated with the rest in a sort 

 of republic, where the labours of all are exerted for the com- 

 mon benefit of the whole society. But it is, perhaps, more 

 consonant with our ideas of the nature of vitality, to consider 

 the extent of the distribution of nutritive fluid in any organic 



