380 PHYTOGKAPHY. 



rosive sublimate as it will take up, then add a trifle more of alcohol, 

 so as to keep the solution just below the point of saturation. 

 The stronger the solution the better, except that, at full satura- 

 tion and where copiously- used, an efflorescence may sometimes be 

 left on the surface of the poisoned specimens upon the evapora- 

 tion of the alcohol. Some add to the solution some carbolic 

 acid, at the rate of a fluid ounce to each quart of alcohol. The 

 solution may be applied with a soft brush (one with no metal in 

 its fastening) ,' or by a dropping bottle, or even the specimens 

 may be dipped in the solution placed in a flat porcelain dish. 

 The brush (using a pretty large and soft one) is the most con- 

 venient and efficient. The moistened specimens should be placed 

 between driers and in shallow piles until the alcohol evaporates. 



805. Thoroughly poison all specimens before admitting them 

 to the herbarium. It is well to poison all specimens whatever, 

 as soon as they are made or at the close of the botanizing sea- 

 son, as well those intended for exchanges as for the collector's 

 own herbarium. 



806. Keep all specimens between sheets of paper, or within 

 folded sheets, not too crowded or overlaid, away from dust, and 

 in a perfectly dry place, so as to avoid mould. When attacked 

 b}' mould, the corrosive-sublimate solution should be applied. 

 A properly dried specimen, dulj' cared for, should be as lasting 

 as the paper which holds it. 



807. The Herbarium, called by the earlier botanists Hortus 

 Siccus, is a collection of dried specimens, named and S3'stemat- 

 ically arranged. It is indispensable to the working sj'stematic 

 botanist, and every devotee of botany should possess, or have 

 access to an herbarium containing representatives of the plants 

 of the immediate vicinity or district, if not of the whole country. 

 Or an herbarium may be restricted to a particular family of 

 plants, made the object of special study. A general herbarium 

 should contain specimens representing all the natural orders and 

 as many of their genera and species as possible. 



808. The form of the herbarium as to the size of its sheets is 

 considerably variable. That of Linnaeus is of the size of foolscap 

 paper : this would now be universally regarded as much too 

 small. The principal British herbaria adopt the size of 16 J by 

 10 J inches, which is rather too narrow, rarely permitting two 

 specimens of the same species of any considerable size to be 

 placed side by side on the same sheet. In the United States, 

 16^ inches in length by llf in width is adopted ; that is, for the 

 genus-covers, the species-paper being a quarter of an inch nar- 

 rower. 



