232 FLORA OF WASHINGTON AND VICINITY. 



euoiigl) iu front to leave the name in fall view, and when the doors are 

 closed this end bends down so as to present it clearly to the eye. If the 

 genus contains only one or two species, or even three, species -strips are 

 not used, but for all genera reijresented iu the duplicates by four or more 

 species, each species is also provided with a strip. Between the genus- 

 strip and the first species a sheet of paper intervenes, so that the two 

 strips will not lie upon each other. Single sheets are alone used to put 

 duplicates on, and great facility is thus secured in handling them. 

 The plants occui)ying each i)artition are placed between large-sized 

 paste-boards, the ui)per one of which is thinner and more pliable than 

 the lower. This latter feature will be found a great improvement upon 

 the use of two stiff boards. 



6. — EXCHANGINa SPECIMENS. 



The duplicates are the botanist's stock in trade. With them he must 

 expect chiefly to enrich his herbarium. This is done through exchanges. 

 His local flora is sure to contain many things that are not to be found 

 in soDiC other places, and every such place will possess species which he 

 cannot find. By notifying other botanists of what he has to exchange, 

 he will receive offers which will be mutually beneficial to both parties. 

 Besides having his duplicates conveniently arranged, he must also pre- 

 pare and keep up a strict list or other account of them. This can best 

 be done by marking them on the check-list of his local flora, if there be 

 one, or on some larger catalogue embracing them all. It is well to have 

 two copies of this, so that in case one is lost iu the mails, all his labor 

 in preparing it will not be also lost. 



When fully prepared to commence exchanging, he consults the Botan- 

 ical Directory and drops a brief note to each of tbe botanists in localities 

 from which he desires to receive plants, inviting them to exchange, 

 some of whom are sure to respond favorably. To such he sends his list 

 of duplicates and requests theirs in return. His correspondents select 

 from his list such plants as they desire, return his duplicates, and send 

 him their lists. In like manner he selects his desiderata from their lists 

 and returns them. If each wants about the same number from the other, 

 the packages are made up and forwarded and the exchange is consum- 

 mated. If there is great inequality, farther negotiations are required. 



In making up packages to send out, each specimen should be accom- 

 panied by a nice permanent label, such as any one would be willing to 

 have attached to it in the herbarium of another botanist. This is chiefly 



