36 FATS, OILS, AND WAXES 



chloroplasts and which he considers to be the first visible 

 product of assimilation, and very much smaller globules, 

 suggesting microsomes, distributed throughout the cytoplasm. 



In many cases there can be but little doubt that fats are 

 produced from carbohydrates ; the work of Schmidt,* Le Clerc 

 du Sablon,-}" and others has shown that as the carbohydrates 

 disappear so fats appear. For example, in the case of the 

 almond the seeds when they begin to ripen are rich in carbo- 

 hydrates and poor in fats, whereas the reverse is true when 

 they are fully matured. The same holds true for the seeds of 

 Ricinus and Pceonia. The nature of the carbohydrates used 

 up in this process varies in different plants ; thus it is stated 

 that in the olive mannitol replaces the carbohydrate. This 

 statement, due to de Luca, is not accepted by other investi- 

 gators of the same plant ; according to Funaro mannitol does 

 not appear until after the oil has been formed. 



" In the case of Ricinus seeds the oil is formed from glucose, 

 and in Pceonia principally from starch. The facts that fat may 

 be translocated as such, provided it be an emulsion sufficiently 

 fine, or in the form of fatty acid and glycerol, suggest that the 

 fats in seeds have not been formed in situ, but have been con- 

 veyed there. This may be true to a certain extent, but con- 

 sideration of the fact that fat will appear as the carbohydrates 

 disappear in immature seeds removed from the parent plant, 

 together with the facts relating to the formation of fats in 

 vegetative organs under the influence of cold (p. 3), leads 

 to the conclusion that the substances in question are formed 

 at the expense of carbohydrates. Further, corroborative evi- 

 dence is afforded by well-ascertained facts relating to similar 

 problems in animals. 



Ivanow,J experimenting with rape seed, has shown that 

 they contain a lipase which may either hydrolyse a fat or may 

 synthesize one from fatty acid and glycerol. Thus, if a 

 glycerol extract of the seed be mixed with oleic acid, fat is 



* Schmidt : " Flora," 1891, 74, 300. 



t Le Clerc du Sablon : " Compt. rend.," 1893, "7> 524 ; 1894, 119, 

 610 ; 1896, 123, 1084 ; " Rev. Gen. Bot.," 1895, 7, 145 ; 1897, 9, 313. 

 X Ivanow : " Ber. dcut. bot. Gesells.," 1911, 29, 595. 



