544 BOTANICAL GAZETTE [December 



oxidation to carbohydrates, but the intermediate products are not known and 

 are the next substances for investigation. Since the unsaturated fatty acids 

 are so readily oxidized to carbohydrates (an exothermic process) during 

 germination, the author concludes that their appearance in a plant is a special 

 adaptation, making rapid germination possible by a great liberation of energy. 

 As long as we know so little about the phsyiological use, if any, made of most 

 of the energy liberated by such oxidations, this conclusion is without evidence 



in its favor. 



A third paper 11 deals with the synthesis of fats in oily seeds. In the flax, 

 rape, etc., the testa is formed first, followed by the development of the embryo. 

 Pentosans accumulate early, having their only role in the formation of protect- 

 ive structures in the testa and playing no part in nutrition. The carbohy- 

 drates (glucose, cane sugar, and starch) are the main substances from which 

 fats are synthesized; while the proteins play a minor if any part in the process. 

 Of the carbohydrates, glucose is first used, followed by the hydrolysis and use 

 of cane sugar, and finally starch. Intense oil formation occupies about two 

 weeks in the middle of the seed development period. Up to the time of the 

 beginning of oil formation, carbohydrates are stored in the stem. At this time 

 the hydrolysis of the carbohydrates in the stem begins, and, due to their 

 transformation to insoluble materials, oils, etc., in the seed, a falling gradient 

 is established in that direction, causing the diffusion to the developing embryo. 

 The first acids formed are saturated, as shown by the iodine number. The 

 author also believes that they belong to the higher members of their respective 

 series, for the Reichert-Meissel number is constant, and it does not vary with 

 the acid number. , It is also concluded that the volatile acids play no part in 

 fat synthesis. The acid number varies greatly in the oil from various plants, 

 being very low in oils from seeds rich in unsaturated acids. The author believes 

 the following scheme shows the main features of oil synthesis in a form like 

 the flax seed. 



glycerine 



.oil 

 saturated fatty acids unsaturated acids 



The variation in the iodine number with stages of development is the 

 greater the greater the proportion of the unsaturated acids in the oil. In 

 seeds with few fatty acid components in their oils (rape and hemp) the 

 variation in the physical and chemical characters of the oil with stages of de- 

 velopment is slight; while in seeds with oils of many fatty acid constituents 

 (flax and poppy) these variations are great. 



It must be remembered that such quantitative analyses cannot certainly 

 determine the series of products and reactions involved in a synthesis, for many 



11 Ivanow, Sergius, Uber den Stoffwechsel beim Reifen olhaltiger Samen mit 

 besonderer Berucksichtigung der Oelbildungsprozesse. Beih. Bot. Centralbl. 28: 



159-191. 1912. 



