COMPENDIUM. 265 



external organs, can be determined, in the others they are often variable, 

 and their purpose must be conjectured. 



In great preponderance, Zoophytes are fashioned as leafless flowering 

 shrubs or trees, their flowers being living animals ; or they resemble 

 some foliaceous vegetable, penetrated by innumerable pores, wherein living 

 animals have a permanent abode, as they form a portion of its substance. 

 They rise, besides as subgelatinous masses, in rude arborescent figure, the 

 surface composed of numberless cells, with animated occupants : they over- 

 spread foreign substances, in carnose investment, or by encrusting calcare- 

 ous tubes, plates, or rings, various in dimensions and arrangement. 



All these are permanently rooted to the same spot ; a few, but very 

 few, comprehended under the general name of zoophytes, are free — enjoy- 

 ing the faculty of the slowest transition, capable of selecting their own 

 abode, and spontaneously affixing and detaching themselves from it. 

 Sometimes they submit to be borne away by the waters. All are of 

 greater specific gravity than the elements wherein they dwell. 



By an inversion of the common course of Nature, belonging to the 

 higher orders of the animal world, whereby the power of progression is 

 denied to them in the earlier stages of existence, the progeny of many 

 zoophytes then possess it in greater extent, and from their origin ; but soon 

 to be lost for ever, when rivetted to the same spot, there they live and die. 



I am not sensible that the young animal, I should rather say the 

 elements or larva, testifies any acute sense in the choice of the place 

 where it shall dwell, otherwise it would certainly shun an unsuitable situ- 

 ation. Its abode seems chiefly the result of accidental circumstances : and 

 it seems to be more from the concurrence of certain conditions, than by 

 preference, that the position proves favourable. 



Nevertheless, the elementary animals may be arrested in their courses ; 

 they may be rivetted unwittingly to the spot they are traversing, as as- 

 suredly is the fate of some originating simple and compound Ascidia?. 



Zoophytes are seated on rocks, on stones, or shells, or on animal and 

 vegetable matter ; and the utmost luxuriance has been witnessed in 

 their diffusion over a metallic substance. 



Amidst the vast variety in all points connected with them, the ulti- 



VOL. II. 2 L 



