CHAPTEE XXI 



THE COLLECTION AND PRESERVATION OF BOTANICAL SPECIMENS 



The study of botany cannot be properly pursued without the pres- 

 ervation of specimens. The mistake is very general of assuming that 

 such material is required only in case of the making of a permanent 

 herbarium. It is necessary besides as a temporary expedient in the 

 thorough study of plants. A plant is not studied until all its parts 

 have been examined. As the mature fruit is rarely present with the 

 flower, and as the stem, leaves and underground portions are liable to 

 present different characters at different seasons, it becomes necessary 

 to make several collections from the same plant and to preserve them 

 to be studied together. There is, moreover, a waste of time involved 

 in using the summer season for dissection and study, when the attention 

 should be directed to field-work. 



Specimens may be preserved in alcohol or in formaldehyde or other 

 solution, or they may be preserved by drying. The latter method is 

 usually employed and is the more generally useful, although it possesses 

 certain disadvantages which will be referred to further on. 



Alcoholic specimens are made by simply immersing the material in 

 alcohol and sealing perfectly. Very fleshy specimens may require a 

 change of alcohol after a time. An improvement on this method is to 

 immerse them in 50 per cent, alcohol for a few days, then transfer them 

 to 75 per cent, alcohol and later to that of full strength (95 per cent.). 

 Alcohol is liable to remove coloring matters and many other substances, 

 as well as to extract the natural water, thus giving to the specimens a 

 shriveled or wrinkled appearance. The use of a formaldehyde solution 

 obviates both of these difficulties, even the most delicate colors being 

 in most cases perfectly preserved. The strength of the solution ranges 

 from 3 to 9 per cent., ordinary water being employed as a vehicle. In 

 the case of fleshy fruits and some other substances, it is found necessary 

 to pour off the first solution and apply a fresh one after a few days, and 

 this renewal may be called for from time to time as the specimens show 

 signs of deterioration. Under the very best of conditions, it must be 

 expected that some changes will occur in the appearance of specimens 

 preserved in solution, and the same is true of those prepared by drying. 



