170 PHYTOGliAPHY. 



sponges excepted. Such a collection of dried plants is 

 called a Herbarium^ and the necessity of herbaries is so ge- 

 nerally felt, that beginners and accomplished botanists justly 

 consider them as their most important treasures. These trea- 

 sures, indeed, are subject, in certain circumstances, to waste 

 and destruction. But, under proper management, and with 

 careful attention, they last for centuries, as we still possess the 

 collection of Caspar Bauhin, and in part that of Burserius, 

 since the beginning of the seventeenth century ; I^Linn, 

 Amcc7i. Acad. I. 146.) 



267. 



The preparation of such a collection costs little labour, and 

 occasions a trifling expence, provided we can obtain a num- 

 ber of folios for this purpose, and are acquainted with some 

 expedients which must be emploved in the work. 



Of these the principal is, that plants must not be laid 

 in while they are wet with rain and dew, but when they are 

 completely dry, and that they be put do^vn with all their ne- 

 cessary parts. Finer plants, which are not too j uicy, and too 

 much soiled, cannot be better dried than in folio sheets which 

 are subjected to some degree of pressure. In this case it is not 

 necessary that the paper should be inspected or changed, till the 

 plants are perfectly stiff and dry. AVhen there is a want of folios, 

 or when soiled or very juicy plants are to be dried, they are 

 placed between several sheets of blotting paper, and pressed 

 down with stones. But in this case they must be frequently 

 turned, and, in particular, must be defended from mouldi- 

 ness. The employment of a press for plants, with a screw, 

 cannot be recommended, because the pressure is too strong, 

 and cannot be gradually increased. Very prickly plants, 

 on the contrary, can only be subduejd in this manner. 

 Fleshy plants are placed for some time in boiling water, and 

 then dried in blotting paper. But in this case the forms and 

 colours are commonly lost. A dry heat is particularly de- 

 sirable in this employment ; on which account the drying of 

 plants always succeeds best in hot summers, in airy dwellingg, 

 in heated roomsj and even beside ovens. 



