flora of washington and vicinity. 225 



4. — Making a herbarium. 



The poisoDing of plants is the last strictly preservative process, and 

 we are now ready to consider the more advanced stages of botanical 

 work necessary to the orderly disposition of the plants identified, col- 

 lected, and preserved. 



The usual course, upon which no useful innovation can be here pro- 

 posed, is to keep each genus, unless too large, in one folded sheet of 

 very heavy paper, called the "genus-cover," to be labeled with the 

 name of the genus on the lower left- hand corner, and to mount the 

 plants on fine white paper,. about IG by 11 inches in size, and place these 

 sheets in the genus-covers. The specimens thus prepared should be 

 kept in the latest api^roved order according to the natural system of 

 classification, in cases either permanently' made for the purpose or porta- 

 ble. These cases should consist of partitions, 13, or better, 14 inches wide. 

 4 or 5 inches high, and 19 inches deep, arranged one above another in sev- 

 eral vertical tiers; these dimensions to be all in the clear, and clear of door- 

 jambs. The doors, which should consist as much as possible of glass, 

 should, if practicable, be so hung that when swung back the edge will 

 be flush With the inner vertical sides of the cases, i. e., leaving no 

 shoulder for the genus-covers to catch upon in drawing them out. 



The labeling of the orders is somewhat difiBcult on account of the per- 

 petually growing and changing character of the herbarium. If labels or 

 tickets are attached to the edges of the shelves, they are sure to require 

 ♦removal in a short time, which disfigures the cases. The best arrange- 

 ment known to me to avoid these consequences and label the families is 

 that of portable order-covers. These consist of good, stiff boards (paste- 

 board) of the same width as the genus-covers and a little longer, to one 

 end of which flaps of the same material are attached by means of strong 

 binder's muslin pasted to both pieces, so that when the large board lies 

 on the package of genus-covers the flap will fall down over their ends 

 and present a vertical surface, upon which the name of the order or 

 orders in the package is placed. The flaps will be three or four inches 

 wide and as long as the board to which they are attached is wide. In 

 the course of time it will often happen that orders once jflaced in one 

 partition and labeled on the flap will have to be taken out and put in 

 another. In such cases the names must of course be erased from one 

 flap and writiten on another. The principal objection to this system is 

 that it requires time and trouble to remove the order-covers every time 

 a plant is wanted. Upon the whole, it is perhaps better to do without 

 Bull. Nat. Mus. No. 22 15 



