CHAPTER IV.
THE PLANTS.
As already stated, the green weeds are most suitable, the red next so, but of the brown and olive sorts there are very few that can be kept in a state of health for any length of time. There are only two plants suitable for the commencement of the experiment, and these are Ulva latissima, the common sea lettuce, and Enteromorpha compressa, a delicate grass-like algæ, of a very cheerful green. Of these Mr. Lloyd and Mr. Hall have always plenty on hand, ready cleaned and prepared for immediate submersion. Artificial water soon acquires the properties of natural sea water under the influence of these plants, which grow rapidly, and disseminate their spores throughout the tank, at the same time giving abundance of oxygen for the support of animal life.
When a few weeks have elapsed Chondrus crispus, better known as “Carrageen moss,” may be added, it is a free grower found in plenty on the ledges at extreme low-water mark. The green weeds Codium tomentosum, Cladophora arcta, and rupestris, and Bryopsis plumosa may be considered safe stock when the water has been in use a month or two, but the growth of the more delicate of the Rhodosperms must not be attempted in artificial water for at least three or four months.
The best weeds of the latter class are Phyllophora rubens, Corallina officinals, and Iridæa edulis. In collecting, no doubt the Dulse, Delesseria alata, and san-
