ON COLLECTING AND PRESERVING PLANTS 35 



with an ordinary pocket-lens or under the microscope. Such en- 

 velopes should be gummed at the back to the sheet of mounting- 

 paper, preferably with the name of the plant and its collection 

 number, if any. These field numbers are quoted, and save much 

 trouble and needless explanation in the event of any subsequent 

 correspondence on the specimens they refer to. In collecting 

 obscure forms and little known varieties and all plants such as 

 Hawkweeds, Willows, Roses, Sedges, etc., in any quantity, all of 

 one gathering should bear the same numeral. This is particularly 

 the custom with collectors of sets of rare plants in new or httle- 

 known countries, and these numbers are referred to and quoted 

 afterwards in books written on the flora of those countries. In 

 working at any special genus or at the plants of one country, whether 

 it be at Petersburg, Vienna, London, or New York, it is a great help 

 to find a collector's specimens all uniformly numbered thus. 



The arrangement of the specimens in genus covers, and of the 

 herbarium generally in a cabinet, must depend upon the individual 

 taste of the botanist and upon the size of his collection. But except 

 in very small collections when several genera can be placed together 

 in one cover, with its name and that of the various genera neatly 

 written outside, it is better to place all the species of one genus 

 only in a cover. These genus covers should be made of stout brown 

 paper folded to a sUghtly larger size than the mounting paper. 

 The name of the genus should be written on the end of the cover 

 so that it can be readily found when packed in the cabinet. As the 

 collection grows it may be necessary to have more than one cover 

 for many of the larger genera. 



Cabinets should be made of well-seasoned wood — what is called 

 American whitewood is a very good and inexpensive material. 

 The usual form is a tail, upright cupboard, divided perpendicularly 

 into two equal parts, and with two closely fitting doors opening 

 in the middle (two doors are very much better than one). The 

 shelves should be made very carefully of thin wood which will not 

 warp, and they should slide easily in shallow grooves cut in the 

 framework of the cupboard. They are better supported in this 

 way than on narrow strips of wood nailed to the sides, for such 

 strips interfere with the papers when the shelves are very full. 



