PHYSIOLOGY 41 



the amount of sugar rapidly increases until in seedlings about 

 4 inches long it may amount to 20 per cent of the dry weight, 

 then a gradual decrease takes place. There is also a small 

 increase in the amount of starch. 



The nature of the carbohydrate differs in different plants ; 

 thus in addition to the above-mentioned plants, during the 

 germination of Allium and of Cucumis much glucose makes its 

 appearance ; this is also true, although to a lesser degree, for 

 Cannabis saliva, in which case the glucose is quickly trans- 

 formed into starch. 



In other instances starch is said to be the carbohydrate 

 formed. 



The consideration of the formulae of the substances in 

 question shows that fats poor in oxygen give rise to carbo- 

 hydrates rich in oxygen, and vice versa ; but as to how this 

 is accomplished nothing of a definite nature is known. 



Many suggestions have been put forward, and before 

 mentioning these the reader may be reminded of the large 

 amount of oxygen which is absorbed during the germination 

 of oil-containing seeds. 



Detmer considered that starch may arise from the free 

 oleic acid according to the equation — 



C18H34O2 + 27O = 2(C6Hio05) + 6CO, + 7H2O. 



This change is supposed to be effected by the oxidation 

 of the chain at the double bond setting free two unsaturated 

 groups which by polymerization give rise to sugar. 



These conclusions are based on the observations that 

 during the germination of the seeds of Arachis the carbo- 

 hydrate increases to 5-6 per cent of the dry weight, whilst in 

 Ricinus the increase is 16 per cent. The glycerol of the fat 

 would be sufficient to form about 5 per cent of carbohydrate ; 

 this roughly was the amount observed in the case of Arachis, 

 whereas in Ricinus the amount of fat was about three times 

 as great. 



It has already been mentioned that glycerol so far has 

 not been demonstrated in germinating fatty seeds ; this may 

 be owing to its powers of rapid diffusion or to the fact that 

 it is used up in the synthesis of other substances. 



