AEOMA OF PLA.NTS.- 9 



highly advisable that steps be taken to investigate the possibilities 

 of our coimtiy in this direction. With our great range of latitude 

 and variet}' of climate and soil, the conditions naturally favorable to 

 the production of such oils and perfumes should be available. Other 

 questions, such as labor and transportation facilities, must be con- 

 sidered. It is probable that by careful, scientific study of the situ- 

 ation the way may be opened for the development of somewhat ex- 

 tensive industries based on the growing and manufacturing in this 

 country of volatile-oil products now either imported or neglected. 

 These industries are already represented by the peppermint, spear- 

 mint, and wormwood products grown in New York, Michigan, Indi- 

 ana, Wisconsin, and other States of the upper Mississippi Valley. 



AROMA OF PLANTS. 

 NATURE OF ODORS. 



Of the countless numbers of plants in the vegetable kingdom, a 

 large percentage possesses peculiar aromatic odors, by means of 

 which the plants may ofttimes be characterized. The substances 

 which impart these peculiar odors to plants consist of mixtures of 

 comi^ounds oily in character and of a volatile nature; hence the 

 designation " volatile oils." 



It may be generally stated that all plants which in the growing 

 condition give off a pronounced odor or which produce this odor 

 when the leaves or flowers are rubbed betAveen the fingers contain an 

 essential oil. However, this must not be construed to mean that all 

 volatile oils must necessarily be derived from plants which possess 

 an odor, there being plants which do not possess the oil pre-formed in 

 the tissues, but which through the interaction of constituents in the 

 plant under proper conditions yield a volatile oil. A common ex- 

 ample of this class of plants or plant products is the bitter almond, 

 which yields the bitter-almond oil of commerce by maceration of the 

 ground kernels with water, the oil formation taking place during 

 maceration. 



The aroma of plants is not necessarily due to volatile oils, there 

 being other odor-bearing substances which, while distinctly aromatic, 

 are not of an oily character. Reference is here made to plants and 

 plant products which, while not possessing any odor during the 

 growing period, develop very fragrant odors after harvesting and 

 drying. An example of this class is the vanilla bean of commerce, 

 which in a green condition is odorless but which when properly 

 cured develops the characteristic fragrant vanilla odor. In this case, 

 according to Lecomte," a glucosidal body in the plant, coniferin, is 



"Lecomte, Henri. Comptes Rendus Hebdomadaires des Seances de TAcadeaiie 

 des Sciences, vol. 133, 1901. p. 745. 



59647°— Bui. 195—10 2 



