174 FUNCTIONS AND INSTINCTS. 



that have no tentacles, and form the fourth Order. 

 These are included by Lamarck amongst those 

 just mentioned, but they appear not properly to 

 belong to them, and to have a still more simple 

 organization. In this tribe, as was before observed, 

 nutrition seems carried on by a kind of systole 

 and diastole, the sea water being alternately 

 absorbed and rejected by the tubes composing 

 the substance of the sponge, they having no 

 organs to collect their food in any other way. 



Many of these productions are remarkable for 

 being hollowed internally, and in their external 

 shape resembling cups, bowls, and vases : several 

 gigantic specimens of this kind were collected in 

 India by the late lamented Sir Stamford Raffles, 

 to whose indefatigable exertions, judicious ar- 

 rangements, and uncommon ardour in her cause, 

 science is so deeply indebted, and presented by 

 him, with the rest of his valuable collections, to 

 the Museum of the Zoological Society, where 

 they are now to be seen. Their general structure 

 also, as well as form, fits them for receiving a 

 large quantity of water, as well as for parting 

 with it, in proportion to the pressure, when 

 received : in the living animal, this pressure is 

 produced by its expansion. 



What particular function, or office, has been 

 devolved by the All-wise Creator upon these 

 zoophytes, which are produced so rapidly, and in 

 such numbers, on the bed of the ocean and its 



