

FORMATION OF FOOD MATERIAL 9 



fruits, etc. In cereal grains and tubers the sugar is 

 again changed back into starch after it has arrived at 

 its destination. 



Pat or Oil. Oil differs from fat in being liquid 

 at ordinary atmospheric temperature, while fat is 

 solid. They are both soluble in ether. These are 

 formed from the carbohydrates, and it appears that 

 a high temperature is necessary for the conversion of 

 carbohydrates into fat or oil, seeing that flax seed 

 (linseed) grown in hot countries (Russia) contains a 

 much higher percentage of oil than that grown in 

 colder climates (Ireland). 



Fat and oil are made up of the same three elements 

 as carbohydrates, but are characterised by having a 

 very small proportion of oxygen in the molecule ; or, 

 to put it another way, fat is exceedingly rich in 

 carbon. 



Amides. The sugar formed in the leaves is carried 

 to all parts of the plant along vessels called the bast 

 (phloeum). It is on this journey that the sugar comes 

 in contact with the minerals, more especially the 

 nitrates, when the living matter in the plant causes 

 the elements of the sugar and the nitrates to combine, 

 forming, probably, first ammonia (NH 3 ) and then an 



/ IT \ 

 amide NiY The amides, therefore, contain 



nitrogen in addition to the three elements found in 

 carbohydrates and fats. They are soluble in the 

 cell sap, and are abundant in young, and especially 

 so in luxuriant herbage. 



Albuminoids. As plants mature, the amides are 

 gradually transformed into albuminoids (proteids). 

 These differ chemically from amides in containing 



