Plant Qrowth'Suhstances 



Chemical Abstracts and British Chemical Abstracts. The horti- 

 culturist, however, may not know of the monthly Experiment 

 Station Record (Washington, D.C., U.S.A.) or of the excellent 

 Horticultural Abstracts issued by the Imperial Bureau of 

 Horticulture, East Malhng, Kent, England. The latter 

 periodical is a quarterly, and costs 6s. 6d. (about $1.50) per 

 issue, or;fi 5s. od. ($6.00) per year. To subscribers to certain 

 other publications of the Bureau the price is reduced 20 per 

 cent. The issue for March 1939 contains about 20 abstracts 

 relating to natural and artificial growth-substances, and that 

 number, which may be expected to maintain itself quarterly 

 for a time, gives an idea of the rate at which knowledge of the 

 subject is expanding. 



The exceptional development already mentioned as of 

 interest to chemists is the discovery that vitamin B^ (thiamin, 

 aneurin) is potent as a growth-regulating substance when 

 applied to plants. Vitamin C (ascorbic acid) acts somewhat 

 similarly. Thiamin, at least, may be a serious rival to sub- 

 stances of the indole-acetic acid type at present used in 

 horticulture. 



In this book little space has been given to the chemistry 

 of the vitamins. Unlike the indole and naphthyl compounds 

 that act as regulators of plant growth, the vitamins have had 

 considerable publicity given to their chemistry. It has been 

 felt, therefore, that chemists will be satisfied with a few leading 

 references to the synthesis of vitamin B^, and that it is hardly 

 necessary to say much at this date about the synthesis of 

 ascorbic acid. Probably most chemists will be more interested 

 to learn of the new field for the vitamins — as drugs capable of 

 regulating plant growth when applied to plants from the 

 outside — than they will be to learn much about the artificial 

 syntheses of vitamins, or of their natural production in or by 

 plants and micro-organisms. It does seem, however, that 

 an understanding of the phytological functions of some vita- 

 mins, when outside the plant, may have great agricultural as 

 well as horticultural importance. 



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