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SCIENCE 



[N. S. Vol. XXXVI. No. 922 



form, Scheele devoted much time to phyto- 

 chemistry, discovering more than a score 

 of important plant compounds besides 

 those mentioned above. Other men fol- 

 lowed in his footsteps and by the beginning 

 of the last century many of the important 

 plant compounds had been isolated. 



At the very beginning of what may be 

 justly called the renaissance in organic 

 chemistry, Marggraf (1745-79) completed 

 his historical work on the common beet- 

 root. With his discovery and preparation 

 of sucrose from the sugar-beet began the 

 first and perhaps the greatest and most 

 highly technical industry of modern times. 

 It was likewise during the close of this first 

 epoch that Pelletier began his classical 

 work on the alkaloids, resulting in the dis- 

 covery of no less than twelve of the im- 

 portant ones, including quinine, strychnine 

 and brucine. In fact, it was during this 

 same epoch that nearly all of the great 

 families of plants were studied from the 

 chemical point of view, resulting, in almost 

 every case, in important discoveries. Even 

 the resins, which chemists have until re- 

 cently regarded as too complex to deserve 

 serious attention, were studied in an indus- 

 trial way and more than thirty different 

 varieties prepared and used in the arts. 

 But the resins were only one of the many 

 groups of organic compounds regarded as 

 too complex to admit of other than a study 

 in the most general way, for organic chem- 

 istry had not advanced far enough to 

 permit of a thorough chemical study of 

 even the simplest of the organic substances. 

 The adoption of the radical and the ring 

 theories about the middle of the last cen- 

 tury, however, completely changed the 

 sphere of organic chemistry and synthetic 

 methods and the chemical constitution of 

 organic compounds became the goal toward 

 which a large majority of chemists worked. 



The adoption of the benzene ring theory, 



together with the working out of the chem- 

 ical constitution of naphthalene, pyridine, 

 quinoline and the terpenes, opened new 

 fields in phytochemistry, and the first ten 

 years of labor after the adoption of these 

 new theories showed amazing results. 



Structural and synthetic work in plant 

 chemistry really began in the sixties. In 

 1869, Lieberman startled the whole chem- 

 ical world by synthesizing alizarine, an 

 important vegetable dye-stuff, and shortly 

 after the alizarine synthesis, Baeyer suc- 

 ceeded in building up the indigo molecule. 



Following these historical discoveries 

 came numerous phytochemical syntheses, 

 one of the most important being the arti- 

 ficial preparation of vanillin. Until Tie- 

 mann had shown that vanillin can be made 

 cheaper in the laboratory than it can pos- 

 sibly be obtained from the vanilla plant, 

 chemists, on the whole, were somewhat 

 skeptical about the practicability of syn- 

 thetic methods and especially as to the pos- 

 sibility of these synthetic compounds sup- 

 planting those produced by nature. The 

 vanillin and the indigo syntheses, however, 

 completely changed the whole chemical 

 world in this respect. Men began to imi- 

 tate nature in the building up of not only 

 the vegetable, but also the simple animal 

 compounds — a few enthusiasts casting long- 

 ing glances at the constitutional formulae 

 of sugar, starch and cellulose, while the 

 ultrachemical investigators dared even to 

 speak in undertones of the structure of the 

 albumins and the resins. Then came 

 Baeyer 's marvelous work on mellitic acid. 

 His exhaustive study of this acid, which 

 began as early as 1867, was so far reaching 

 in its application to the ring compounds 

 that it had much to do with final working 

 out of the structural constitution of the 

 terpene group. 



There is a universal feeling, I think, 

 among those who have watched the devel- 



