from the South Coast of Devon. 13 



smaller and thus less-marked cellules may exist iu all ; but 

 as yet I have not been able to substantiate this. 



Of course, after having been chied, it is impossible to make 

 out any thing in these cells so satisfactorily as in living ones ; 

 and hence, although such cells are present in great abundance 

 in their contracted state in the dried specimens of Geodia 

 gigas mentioned (measiu'ing about a 1000th of an inch in dia- 

 meter and filled with a number of ceUules), liquor potassa^, 

 although it causes the cellules to run together into one homo- 

 geneous mass, does not yield any satisfactory demonstration 

 of a nucleus under the addition of nitric acid, nor is the cell- 

 wall well marked — two points in which the cell of Dercitus 

 niger differs distinctly from the ampullaceous sac. 



Hence the desirableness of examining these cells of G. gigas 

 in the recent state. 



We too often content ourselves with describing sponges as 

 well as other objects of natural history in their dried or dead 

 condition ; and although this is the only way in which they 

 often come to us, yet we might as often repeat to ourselves 

 as well as to others under such circumstance the words of 

 Hamlet to Horatio : — 



" There are more thingrs in heaven and earth, Horatio, 

 Than are dreamt of iu yom- philosophy." 



Too often the living state of such objects is disregarded 

 when we have the opportunity of adding this sine qua non to 

 their natural history. Describing the skeleton or dried speci- 

 men of a sponge only is little better than making it a matter 

 of mere cmuosity ; and hence the want of general interest and 

 comparatively little advancement which characterizes our 

 knowledge of this more than any other division of the animal 

 kingdom. 



I am not, however, yet satisfied with my examination of the 

 cells of Dercitus niger and Stelletta aspera^ although partly 

 made in the living state ; for I cannot yet fully comprehend 

 the nature of the nucleus in respect of its large size, resem- 

 blance to an aqueous cavity, and indisposition to change its 

 appearance under the application of chemical agents. 



In short, we have yet much to learn about this cell before 

 we come to its real import ; meanwhile its notice adds another 

 feature to the Pachytragous Sponges, some of which possess 

 analogous elements, as the globular crystalloids or little sili- 

 ceous balls in the Geodida, akin to which are the siliceous disks 

 of a like natm'e in Stelletta discophora^ Schdt. ; while others 

 possess neither cells, globular crystalloids, nor disks, as Stel- 

 letta lactea. 



