262 POLYZOA INFUNDIBULATA. 



The ova, as Professor Grant discovered, proceed from no 

 peculiar organ in the body of the polype, but from the 

 " common connecting medium, 11 and only differ in their origin 

 from the gemmules in pullulating from its inner surface ; * 

 and a wider survey of the class has folly confirmed this dis- 

 covery. Germinating in every species from the inner surface 

 of that portion of the skin or coat which lines the interior of 

 the cell, the ovum falls, when mature, into the space between 

 it and the body of the polype ; and in this cavity, which is 

 always full of a fluid, probably sea-water, it grows and 

 appears to be rendered fruitful by admixture with the sperma- 

 tozoa that are there prepared for this union. In many genera 

 ova are produced also in thin calcareous capsules, which lie 

 over and above the apertures of the polype cells ; but even in 

 them the matrix is the lining membrane, and this is identical 

 with that of the cell itself. Wherever produced the ova are 

 globular or ovate, or have a tendency to these shapes, and 

 the surface is clothed with vibratile cilia ; yet not univer- 

 sally, for ova without cilia have been detected both in the 

 cells and capsules, and they have been seen apparently ready 

 to escape outwardly in this naked condition,^ although it is 

 conjectured that cilia are subsequently developed. It is by 

 means of these microscopic organs that they are moved to and 

 fro, first within the sac of the parent cells, and then after 

 birth throughout " this great and wide sea," so to fulfil their 

 mission in creation, and people the shores of every clime with 

 myriads of busy workers in horn and in lime, which, with 

 subtile chemistry, they draw from a fluid quarry, and build 

 up in textures of admirable beauty and heaven- ordered de- 

 signs. " how desirable are all His works ! and that a man 

 may see even to a spark. All these things live and remain 

 for ever for all uses, and they are all obedient. All things 

 are double one against another : and HE hath made nothing 

 imperfect. One thing established! the good of another : and 

 who shall be filled with beholding His glory. 11 Ecclesiasticus. 



* Edin. New Phil. Journ. iii. p. 116-17. 



t Reid in Ann. and Mag. Nat. Hist. xvi. p. 399. Several of the ciliated in- 

 fusorial animalcules described by Mullcr and others appear to be merely the ova of 

 polyzoan polypes. 



