COLLECTING AND PRESERVING. 181 



Only one species or variety should be placed on a sheet. Speci- 

 mens which are taller than the length of a sheet should be 

 doubled over when they are pressed. The species of a genus 

 are collected into a genus cover. This cover is a folded sheet of 

 heavy manila or other firm paper, and the standard size, when 

 folded, is 12 x 16J inches. On the lower left-hand corner of 

 this cover the name of the genus is written. A label should 

 accompany each specimen upon the separate sheets, recording 

 the name, date of collecting, name of collector, and any notes 

 which may be of interest. The specimens are now ready to be 

 filed away on shelves in a horizontal position. If insects attack 

 the specimens, they may be destroyed by fumes of bisulphide 

 of carbon (see Chap. I.) or chloroform. In this case it is neces- 

 sary to place the specimens in a tight box and then insert the 

 liquid. Lumps of camphor placed in the cabinet are useful in 

 keeping away insects. Usually, however, specimens are dipped 

 in poison, and then dried before being mounted. 



HERBARIUM POISONS. 1. 120 grains of arsenic acid dissolved 

 in a quart of alcohol. The arsenic acid is very deliquescent and 

 the bottle must be kept tightly corked. This is Dr. Gray's 

 favorite preparation for use in the herbarium at Harvard Uni- 

 versity. 



2. Place as much corrosive sublimate in alcohol as the liquid 

 will dissolve. If the poison is applied with a brush, care must 

 be taken to avoid one with iron trimmings, as the sublimate cor- 

 rodes the iron. 



3. Dissolve If ounces of corrosive sublimate in 1 pint of alco- 

 hol ; add 2J fluid drams of carbolic acid, and apply with a 

 paint-brush. 



4. 1 pound of corrosive sublimate, 1 pound of carbolic acid 

 to 4 gallons of methylated spirit (wood alcohol). 



2. Preserving, Printing, and Imitating Flowers and Other 

 Parts of Plants. 



To PRESERVE THE COLOR OF DRIED FLOWERS. 1. Im- 

 merse the stem of the fresh specimen in a solution of 32 parts 

 by weight of alum, 4 of nitre, and 186 of water for two or three 



