MOUNTING THE SPECIMENS 231 



the fresh dryers without opening. Under the above treatment, in hot 

 and very dry weather, most specimens will be dried perfectly in from 

 three to four days. Upon the tablelands of Mexico and similar localities 

 only half of this time is required. Many plants, such as orchids or 

 cactuses, may require all summer for drying and are even frequently 

 worn out in the process of changing before they become dry. Such 

 plants may be dipped for an instant in boiling water before being dried. 

 This process, while it greatly expedites drying, is apt to make the 

 specimen turn black. 



Great judgment is required to avoid regarding a specimen as dry 

 before it really is so. The test is to see that any part will snap o£F in 

 attempting to bend it. Even after the specimens are perfectly dry they 

 should not be sealed up at once, as they are liable to undergo a sweating 

 process during the succeeding day or two. They should be tied tightly 

 in bundles and these bundles exposed to the sun for an hour or two on 

 several successive days, after which they may be sealed up, a good 

 method being to wrap them tightly in waxed paper, this protected by 

 heavier paper, for transportation through a moist climate. 



Poisoning the Specimen. — Various methods have been resorted to 

 for poisoning specimens so as to make them proof against the attacks 

 of the small insects which infest the herbarium, but in no case have the 

 results proved permanent. Arsenical and mercural solutions have been 

 most employed. Upon the whole, a saturated alcoholic solution of 

 corrosive sublimate is the most satisfactory poisoning agent. Theo- 

 retically, the corrosive sublimate soon becomes converted into calomel, 

 but in practice its effects, if it be thoroughly applied, last for a great 

 many years. It may be poured upon the specimen, applied with a brush, 

 heavily sprayed from an atomizer, or the specimen dipped into it. It 

 is to be treated as a very dangerous poison, not only internally, but 

 highly irritating to eyes, nose, and lungs and capable of poisoning by 

 inhalation of the spray. 



When insects are found attacking mounted specimens, the latter 

 should be enclosed in a tight case and subjected for some hours to the 

 vapor of carbon disulphide. 



Mounting the Specimens. — For permanent mounting in the herbarium, 

 sheets of standard size (IGixllf inches) should be used and the 

 paper should be white and very heavy. Much paper now made of 

 wood-pulp quickly becomes yellow or brown, and scrupulous care to 

 avoid this quality should be taken. The specimens are to be secured 

 by the use of white glue applied over the entire surface and the stems 



