HEEBORIZATION. 377 



several hours afterwards. The stubbornness and elasticity, so 

 troublesome in specimens when first put in, will then have 

 mostly disappeared, and the whole specimen will be found suffi- 

 ciently flaccid to have every part stay as arranged. If this first 

 change is deferred longer than ten or twelve hours, the speci- 

 mens of many species become too dry for making the alterations 

 required. At this time small pieces of bibulous paper may be 

 placed between leaves, or other portions of the plant which over- 

 lap, to prevent moulding or discoloration, and to hasten dr}ang. 

 It is well to change these fragments of paper with the driers for the 

 first day or two : afterwards they may remain with no detriment. 



793. To have the specimens retain their natural color and 

 general appearance, they should be dried as rapidly as possible ; 

 and this result is best secured by frequent changing of the driers. 

 These should be changed at least once a day for the first four or 

 five days, and afterwards every other da}-, until the specimens 

 are thoroughly dried. But a marked improvement in the speci- 

 mens will result from more frequent changes during the first 

 day or two. The first day with Grasses, Sedges, and their allies, 

 and the first two days with most other plants, are of more impor- 

 tance than all the subsequent time. As an experienced collector 

 declares : " Two or three changes of the driers during the first 

 twenty-four hours will accomplish more than a dozen changes 

 after the lapse of several days. The most perfect preservation 

 of the beautiful colors of some Orchids has been effected by 

 heating the driers and changing them every two hours during 

 the first day." 



794. Heated driers are very efficient ; and the best mode of 

 heating is to expose them to the sunshine, and bringing them in 

 hot to make the change at once, or as soon as possible. 



795. The number of driers interposed between the specimen- 

 sheets should depend upon the plants and the frequency of the 

 changes : two will suffice when the driers are changed very often ; 

 but more must be employed when the plants are thick and succu- 

 lent. Uniform pressure may be secured with large and coarse 

 plants by placing strips of pasteboard or pieces of cotton-bat- 

 ting about the sides of the package. Ringlets of cotton may be 

 placed about some of the larger flower-heads of the Compositse, &c. 



796. The time required to dry specimens varies with different 

 species and with the season : it depends also on the frequency 

 of the changes and the temperature of the driers. By changing 

 daily, the time is usually from four or five days to a week. But, 

 with two changes a day for the first day or two and with heated 

 driers, the process may be completed in half the usual time, ana 



