FLUSTRA. 31 



Here is a ready example of how much the luxuriance of such products 

 depends on their situation. 



Perpetuation. — The quality of this subject, so unlike the elementary 

 combination of other zoophytes, and of the Flustrse in particular, induced 

 me to search very earnestly after the mode whereby the species is per- 

 petuated. I conjectured that some analogies might be recognised between 

 it and the Cristatclla, or rather the Alcyonella of the fresh-waters, from 

 the obvious parallel of various features in their history, — I sought in vain 

 — numerous seasons elapsed, all unsatisfactorily, — and here is one noted 

 instance where the profusion of specimens proved of no avail. 



But the hydroe are of difficult preservation. Constant renewal of the 

 agitated waves, appears to be an indispensable lotion, otherwise a thin 

 mouldy film covers the surface of the Flustra, and the hydra; drop from 

 their cells. 



Hence may be discovered the purpose of Nature in placing the abode 

 of this zoophyte within the flux and the reflux of the tide. 



The reader accustomed to observations on points of obscurity, will 

 find no exaggerations here. 



Having selected several vigorous specimens, in the end of May, and 

 committed them to suitable vessels, I soon discovered an animalcuhuu 

 there, quite different from any that had been previously observed amidst 

 all the varieties seen, either in fresh or in salt water. From its external 

 aspect, I was inclined to class it with some of the more uncommon Infu- 

 soria. Others, in sufficient number, were produced in June, which is the 

 principal period of their maturity. 



This creature, the gemmule of the Flustra hispida, is pure white, 

 elliptical, thin, and fringed by a border of active cilia, — all which renders 

 it a beautiful object under the microscope. It traverses the water readily 

 everywhere, ascending, descending, and following various courses : and 

 some perform a kind of revolution, as if on an axis, towards the front. — 

 Fig. 8. 



In a few days this gemmule remains stationary, and becomes affixed 

 to the spot whereon it has rested ; and in a few more a hydra is generated. 



