1599. The extent requisite for a botanic garden depends upon that of the collection intended to be formed; as well as on the magnitude to which the tree-plants are intended to be grown. A good deal will depend also on whether tender exotics are to be principal or secondary objects of collection, and also on the manner of growing the hardy herbaceous plants. An immense collection of herbaceous plants may be included in a small space, if the soil is loamy, and rather inclined to moisture; and if the plants are separated from each other in the rows by bricks or thin tiles, which at once completely divides them and stints their growth, so as to admit a great number being planted on the same space. The extent of the Chelsea garden is little more than three acres; that of the original Liverpool garden is five acres; and in both are extensive collections. Messrs. Loddiges have above a thousand species of herbaceous plants, which they keep constantly in small pots, set on beds of scoria. These occupy very little space, and the plants thrive well. Of course the larger-growing kinds are excluded.