APPENDIX. 



Marine Vivaria. (See p. 228, et seq.) Since the former 

 note was written in September last, on the keeping of 

 marine animals alive in unchanged Sea-water, I have 

 continued the prosecution of experiments on the same 

 subject, with the most gratifying results. Actinise of 

 different species and other interesting animals, brought by 

 me from Devonshire, are now living in the highest health 

 in London, some of which have been in confinement 

 nearly eleven months. 



The following facts may be considered as established- 

 Marine animals and plants may be kept in health in glass 

 vases of sea- water for a period of greater or less length 

 according to circumstances, provided they be exposed to 

 the influence of light. The oxygen given off by healthy 

 vegetation under this stimulus, is sufficient for the support 

 of a moderate amount of animal life; and this amount can 

 be readily ascertained by experiment. 



But another element in the question soon obtrudes 

 itself. The Actinise and other animals habitually throw 

 off a mucous epidermis, and other excretions, which fall to 

 the bottom of the vessel, or accumulate around them. 

 The process of natural decay also continually goes on in 

 the older fronds of the Algae. Here then there is a con- 

 tinually increasing deposit of organized matter in a 

 state of decomposition ; and after a while the presence of 

 this substance becomes too manifest in the offensive odour 



