434 THE AQUARIAN NATURALIST. 



upon their axis, or they tumble over and over ; or, 

 selecting a fixed point, they whirl round it in rapid 

 circles, like moths around the flame of a candle; 

 others creep along the bottom of the watch-glass, upon 

 one end, and with a waddling gait, until in a short 

 period all motion ceases, and they are found to have 

 attached themselves to the surface of the glass, where, 

 after the lapse of about forty-eight hours, the rudi- 

 ments of a cell may be observed in process of forma- 

 tion, indicating the commencement of a new colony. 

 In these forms of Polyzoa there is moreover a 

 second mode of reproduction, namely by gemmation, 

 that is, by the development of young animals and 

 cells in the interspaces between the mature ones ; 

 and this may readily be witnessed in every specimen. 

 The newly-formed cells thus produced are, at first, of 

 a triangular shape, and the nascent polyp is to be de- 

 tected as a mere spot in the centre of each. As they 

 grow, they advance outwardly, thrusting aside the 

 circumjacent cells, until they acquire the hexagonal 

 form of the adult, and thus enlarge the population of 

 the colony. We find consequently in these wonder- 

 fully-constructed microcosms two distinct modes by 

 which propagation is effected ; one through the agency 

 of locomotive gemmules, which, by the aid of their 

 cilia, disperse the race to distant localities; and the 

 other by a process of budding, whereby, as in the 

 growth of leaves on a plant, innumerable inhabitants 

 are added to the original colony, which in process of 

 time becomes peopled by thousands, ay, even by 

 millions of exquisitely-constructed creatures, present- 

 ing altogether a scene of life and happiness, the con- 



