12 THE PRODUCTION OF VOLATILE OILS AND PERFUMERY PLANTS. 



The fruit oils occupy a position of no little importance, represent- 

 ing an industry by themselves. The principal oils from the citrus 

 fruits are obtained from the lemon, sweet orange, bitter orange (petit 

 grain), and bergamot. In all of the above fruits the essential oil 

 is contained in the peel of the fruit from which it is obtained. 



Many of the various seed oils are very important commercially, 

 being employed largely as perfumes and medicinal agents. Among 

 the seed oils derived from the order Umbelliferse (parsnip family) 

 which possess especial value may be mentioned caraway, anise, fen- 

 nel, and coriander. Other seeds yielding oils of commercial import 

 are cardamom, American wormseed, mustard, bitter almond, peach, 

 and apricot seeds. 



In addition to the above and playing an important role in volatile- 

 oil production are the bark and wood oils, the former being repre- 

 sented by such oils as sassafras, canella, and cinnamon. The wood 

 oils comprise such oils as sandalwood, copaiba, and cedar, while from 

 the woods indirectly are obtained several essential oils of value, 

 namely, oils from oleoresins, as turpentine, copaiba, elemi, California 

 turpentine {Pinus sahiniana), and Oregon balsam oil. 



There are comparatively few root oils, the chief examples being 

 valerian, snakeroot, and sassafras oils. 



The aerial portion of the plant serves possibly more extensively 

 for the extraction of volatile oils than any other of the plant parts 

 mentioned. Peppermint, spearmint, and wormwood, from which 

 oils are now produced commercially in this country, are typical 

 instances. 



DEVELOPMENT OF AROMA. 



The development of the aroma in a plant is conditioned by the 

 interaction of several important factors. It is generally accepted 

 that a close relationship exists between the growth of the plant and 

 climatic factors, such as heat, light, and moisture, and it seems clear 

 also that these conditions play an important part in the formation 

 of the aroma and materially influence its quality. The effect of 

 climate upon the quality of the aroma is clearly shown by the vary- 

 ing fragrance of the oils jiroduced by plants of the same species Avhen 

 they are grown in sections having a wide diversity of climatic con- 

 ditions. Continuous sunshine, Avhich may be a factor in the develop- 

 ment of fragrance in one plant, may possibly exert a reverse action 

 upon another in which the formation of the chief odoriferous con- 

 stituents is not directly favored by the action of light. Usually, how- 

 ever, sunshine is a favorable agent for the production of delicate 

 aromas, while, on the other hand, cloudiness or darkness has a tend- 

 ency to lower the production of aromatic substances by the plant. 



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