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 vegetability 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 1 think, 

 must be assigned the honour of the first accomplish- 

 ment of this object.f His words are as follows : — 



* On the Gro%vth of Plants, p. 73. 



f Since the publication of the first edition of this Work, other 

 competitors for the honour of having first invented the Aquarium 

 have appeared. In a lecture delivered before the Royal Institution, 

 by Dr. S. H. "VYard, the following statements occiir : — " Mr. Ward, 

 in 1841, established, in a capacious earthenware vessel, an Aquarium 

 for fish and plants. In this vessel, which contained twenty gallons 

 of water, and which he siirrounded with rock-work raised several 

 feet above its margin, he placed gold and silver fish, in- company 

 with several aquatic plants, viz., Valisneria spiralis, Pontederia 

 crassipes, Plstia stratiotes, and Papyrus elegans. In this miniature 

 lake, the water of which was never changed, but kept in a con- 

 stantly pure state by the action of the associated plants, the animals 

 lived in a healthy condition for many years." " The individual to 

 whom is due the merit of having introduced marine vivaria into 

 London is Mrs. Thynne. Having procured some living madrepores 

 when at Torquay, in the autumn of 1846, she placed them in some 

 sea-water in a bottle covered with a bladder, and brought them 

 safely to to-^Ti. They were then transferred to two glass bowls, 

 the sea-water being kept aerated by being daily poured backwards 

 and forwards, and being, moreover, periodically renewed by a fresh 

 supply from the coast. In the spring of 1847, Mrs. Thynne sent for 

 some pieces of rock, shell, &c. to which living sea-weeds were 

 attached, and subsequently depended upon the action of these for 

 the purification of the water." Mrs. Thynne has kindly favoured 

 me with a perusal of her observations, which not only prove her to 

 have succeeded in maintaining a self-supporting Aquarium, but are 

 of the highest interest in a physiological view. — {Second Edition.) 



