ON POLYPS. 47 



here studded with minute tubercles, but never provided with cilia. 

 Few objects are more admirable than these polyps, when watched 

 with a good microscope : protruding themselves beyond the mouths 

 of their cells, they inflect their bodies in all directions in quest of 

 prey, waiting till some passing object impinges upon their tenta- 

 cula, which is at once seized and conveyed into the stomach with 

 a rapidity and dexterity almost beyond belief. 



The multiplication of these singular animals appears to take place 

 in three different modes : 1st, by cuttings, as in plants ; Sndly, 

 by off-shoots, or the formation of new branches bearing polyps ; 

 3dly, by gemmules capable of locomotion. 



(66.) The first mode strikingly resembles what is observed in the 

 vegetable kingdom ; for as every branch of the plant-like body 

 contains all the parts necessary to independent existence, it can 

 hardly be a matter of surprise that any portion, separated from the 

 rest, will continue to grow and perform the functions of the entire 

 animal. 



(67.) The second mode of increase, namely, by the formation of 

 new branches and polyps, seems more like the growth of a plant than 

 the developement of an animal. We will consider it under two 

 points of view : first, as regards the elongation of the stem ; secondly, 

 as relates to the formation of fresh cells containing the nutritive 

 polyps. On examining any growing branch, it will be found to be 

 soft and open at the extremity, and through the terminal orifice, 

 the soft tegumentary membrane above described as forming the 

 tube by its conversion into hard substance is seen to protrude ; the 

 skeleton is not therefore merely secreted by the enclosed living 

 granular matter, but it is the investing membrane, which continually 

 shoots upwards, and deposits hard material in its substance, as it 

 assumes the form and spreads into the ramifications peculiar to 

 its species, 



(68.) Having thus lengthened the stem to a certain distance, the 

 next step is the formation of a cell and a new polyp, which is accom- 

 plished in the following manner :* the newly formed branch has at 

 first precisely the appearance and structure of the rest of the stalk 

 of the zoophyte, (Jig. 15, 1,) being filled with granular matter, 

 and exhibiting in its interior the circulation of globules already 

 described, moving towards the extremity along the sides of the 

 tube, and in an opposite course in the middle ; the end of the 

 branch, however, before soft and rounded, soon becomes perceptibly 



* Lister, Philosophical Transactions, Loc. cit. 



