178 FUNCTIONS AND INSTINCTS. 



by the coral fishermen, in the course of a very 

 few years, is again replenished with it. It is 

 probably enabled, by its broad well fixed base 

 and rigid axis, to withstand the violent action of 

 the strong currents of the sea just mentioned. 



6. The Floating Polypes, which form Lamarck's 

 last order, chiefly differ from the coral in being 

 locomotive, and sometimes swimming freely about 

 in the sea, though some usually remain stationary, 

 but never fixed. Their oviform germes, like those 

 of many other marine polypes, are ejected by the 

 mouth. The most noted species, from its sin- 

 gular resemblance to a quill with its plumes, is 

 called the sea-pen. 1 It is a phosphoric animal, 

 and emits a light so brilliant that by it the 

 fishermen can see the fishes swimming near it, 

 so as to be able to cast their nets. 



The vast number of marine animals that are 

 endued with the remarkable faculty of emitting 

 light, indicate that it answers some important 

 purpose in their economy. A fact observed by 

 the celebrated Navigator Peron, renders it pro- 

 bable that its object is defence; he remarked that 

 when the Atlantic Pyrosome 2 was irritated, as 

 well as when it was contracted, its phosphores- 

 cence was augmented. A variety of hypotheses 

 with respect to the phosphorescence of the ocean 

 have been started ; at first it was attributed to 



1 Pennatula an/entea. ~ Pyrosorna atlanticum. 



