366 FUESH-WATER, ALG.E. \_Diatomace(E. 



constituting the plant. Tliese two segments or valves were 

 connected by a tube, which lengthened as we have seen in 

 Micrasterias, and gradually formed two new valves. These 

 grew and parted asunder the two original valves, and the 

 new, joining with the old, formed two cells instead of one. 

 This process is repeated till a filament is formed, several 

 inches in length, and consisting of numerous cells ; the two 

 segments at the end of the filament, though now far sepa- 

 rated, being the two valves or segments of which the original 

 cell consisted. 



Mr. Ealfs has a long and able dissertation on a disputed 

 point, whether the Desmidiea are animal or vegetable, and 

 proves very satisfactorily that they are vegetable. 



In conclusion, we may advert to a curious fact, mentioned 

 by Mr. Ealfs, of II//alofhecaf and other Besmidiecc, being 

 found growing in an old water-butt, in water derived from 

 the clouds alone. Did these pkmts descend from the clouds ? 

 Yes, but they liad previously ascended from the earth. The 

 " High and Lofty One" disdains not to provide for the 

 continuance and wide diffusion of what lie has in wisdom 

 made. To the seeds of many land-plants He gives what 

 serves all the purposes of wings. To the spores of many 

 minute aquatic plants He gives, by means of cilia, the 



