THE VEGETABLE KINGDOM. 131 



tea, and oaks : to prevent this, these seeds should be placed 

 in sandy earth, two inches of this earth should be laid on the 

 bottom, and the seeds put at a little distance from each other, 

 they are then covered with a layer of earth one inch in thickness, 

 and proceed in this manner till the box is filled within six or 

 eight inches of the top, and the remainder filled up with sand. 

 The box must not be too tightly covered, as it is of consequence 

 that the air should penetrate the earth. Indeed, there ought 

 to be an opening at the top, with a trellis cover of brass wire, 

 to prevent the intrusion of mice ; this was the manner in which 

 M. M. Michaux, senr. and junr. transported nearly the whole of 

 the North American oaks to France. During the passage the 

 seeds will germinate, and their embryos will be developed, and 

 all that is required is to place them in fresh soil congenial to 

 their habits. The same method must be adopted with stone 

 fruits, such as walnuts, plumbs, and nectarines; as also with 

 laurels and myrtles, and more particularly those species which 

 have to be transported across the equatorial seas. 



For the preservation of the seeds of pulpy fruits, a different 

 mode must be pursued. These seeds are perfectly ripe when 

 the fruit indicates the first stages of putrefaction, the seeds 

 must then be removed, thoroughly dried, and placed in paper 

 bags for preservation. 



DRIED PLANTS. These are collected for the formation of 

 herbariums, and are of much use in enabling the botanist to 

 describe and distinguish new species. By means of these 

 alone, the naturalist can determine all the characters of the 

 plants, and thus form a classification of the vegetable king- 

 dom. Besides the leaves and stem of the plant, its roots should 

 also be procured if possible. 



Fruits in a ripe state preserved in spirits are extremely use 

 ful for comparison with those which we raise in Europe. 

 Resins, gums, and all other substances which are likely to 

 prove useful in the arts or medicine, ought to be procured. 



The plants intended for an herbarium, must be gathered both 

 in the flower and fruit ; they must be laid out in as natural a 

 manner as possible between leaves of paper, with a board 

 placed over them, and some stones or other weights for pres- 

 sure, to prevent the leaves from curling upon drying. This 

 pressure must be applied till they are perfectly dry, and they 



