DR. Johnston's experiment. 7 



air, with the quantity of vegetable matter required, 

 as compared with the size and rank in creation of the 

 animal, would be a problem well worthy of solution."* 



In the same year (1842) Dr. Johnston published 

 his "History of British Sponges and Lithophytes," 

 in which, arguing out the vegetahility of the latter, he 

 mentioned in a note what is the most germane of all 

 to our purpose, — the actual formation of a little 

 Marine Aquarium. To Dr. Johnston therefore, as I 

 think, must be assigned the honour of the first 

 accomplishment of this object. His words are as 

 follows; — 



" Was there a need of adding any additional proof 

 of the vegetahility of the Corallines, an experiment 

 now before me would seem to supply it. It is now 

 eight weeks ago since I placed in a small glass jar, 

 containing about six ounces of pure sea-water a tuft 

 of the living Gorallina officinalis, to which were at- 

 tached two or three minute Gonfervm, and the very 

 young frond of a green Ulva ; while numerous EissocB, 

 several little Mussels and Annelides, and a Star-fish 

 were crawling amid the branches. The jar was placed 

 on a table, and was seldom disturbed, though occa- 

 sionally looked at; and at the end of four weeks, 

 the water was found to be still pure, the MoUusca and 

 other animals all alive and active, the confervse had 

 grown perceptibly, and the coralline itself had thrown 

 out some new shoots, and several additional articula- 

 tions. Eight weeks have now elapsed since the experi- 

 ment was begun, — the water has remained unchanged, 



•On the Growth of Plants, p. 70. 



