BULLETIN 39, UNITED STATES NATIONAL MUSEUM. [32] 



It will uot be fouud necessary to poison most of the cryptogamous 

 plants, such as mosses, liverworts, horsetails, algse, aud sterile ferus, 

 as they are mostly of loose cellular structure. But fruiting ferns had 

 best be poisoned, aud this can be done by sprinkling better than by im- 

 mersion, as they are likely to have the color destroyed if again thor- 

 oughly wetted. The fleshy fungi and all leaf fungi must be poisoned or 

 they will be speedily destroyed. The specimens should be immersed iu 

 the alcoholic solution of corrosive sublimate as recommended for llow- 

 eriug plants. 



MAKING AN HERBARIUM. 



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

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

 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 16 by 11 inches in size, and place 

 these sheets in the genus covers. The specimens thus prepared should 

 be kept iu the latest approved order according to the uatural 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 oue above another 

 in several vertical tiers ; these dimensions to be all iu the clear, and 

 clear of door jambs. The doors, which should consist as much as possi- 

 ble 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 difficult 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 gen us- 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 3 or 4 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 placed in oue parti- 

 tion 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 



