244 THE MICROSCOPE. 



other excretions, which fall to the bottom of the vessel, or accumulate 

 around them. The progress of actual decay also continually goes on in 

 the older fronds of the algae ; after a while the presence of this sub- 

 stance becomes too manifest in the offensive odour of the water ; in a 

 very short time this leads to disease, and the death of the animal. To 

 prevent this, it is absolutely necessary to present the water to the action 

 of the atmosphere in a divided state, which can only be effected by 

 passing it in driblets, or in a slender stream, from another vessel 

 suspended above that which contains the animals and plants. An- 

 other advantage is secured by this process, viz. the aeration of the 

 water ; for though the requisite oxygen may be supplied by the 

 agency of the plants alone, the mechanical admixture of the atmo- 

 spheric air with the water by artificial aeration is highly conducive to 

 the health and comfort of the animals." 



We must, as a fitting addenda to the above, give the plan pursued 

 by Mr. Gosse, to establish his marine vivarium on a small scale. " The 

 first thing to be done, is to obtain the algsd in a growing state. As 

 they have no proper roots, but are generally found closely attached to 

 the solid rock, from which they cannot be torn without injury by 

 laceration, I have always used a hammer and chisel to cut away a 

 small portion of the rock itself, having ready a jar of sea-water, into 

 which I dropped the fragment with its living burden, exposing it as 

 little as possible to the air. The red sea-weeds I have found most 

 successful ; the Fuci and Laminarice, besides being unwieldly, discharge 

 so copious a quantity of mucus as to thicken and vitiate the water. 

 The Ulvce and Enteromorphce > on the other hand, are apt to lose their 

 colour, or become a colourless membrane, and decay from their attach- 

 ments. The species most capable of being preserved are Chondrus 

 crispus, the Delessaria, and Iridea edulis. The last named is the best 

 of all, and next to it the Delessaria sanguinea, for maintaining the 

 purity of the water ; while the colours and forms of these render them 

 very beautiful objects in the vase. Into this were placed specimens of 

 Anthea cereus, Actinia, Crisia denticulata, Coryne, Pedicillina Belgica, 

 Membranipora pilosa, Doris, Polycera, /Serpula, Acarida, Entomos- 

 traca, Infusoria, Grantia nivea, and other smaller zoophytes and 

 sponges." Most of these appeared to enjoy existence, and afforded, no 

 doubt, months of most interesting microscope examinations j at the 

 same time the vivarium will form a beautiful and attractive ornament 

 for the conservatory or drawing-room. 



Mr. Warington, in his trials, found that it was not sufficient that 

 there be plants alone ; but where the higher animals, such as fish, are 



