I 



THE CARBOHYDRATES PRODUCED IN CROPS 117 



we say that there is about 5 per cent, of sugar in those twenty- 

 four millions of tons ; that is to say, there is well over a 

 million tons of sugar grown in the British Isles and eaten 

 chiefly by cattle in the form of turnips and swedes. In 

 addition to that, there are about ten millions of tons of 

 mangolds grown, which, on the average, will have a rather 

 higher percentage of sugar. Taking all together, there 

 cannot be much less than one and a half millions of tons of 

 sugar produced in the British Isles and consumed in this 

 way, or, roughly, one-tenth of the world's production of 

 cane and beet sugar. In the case of the mangold, much of 

 the sugar is cane sugar, in the case of turnips and swedes much 

 of it is glucose. The crops of swedes, turnips, and mangolds 

 all present some points of similarity, requiring good manuring 

 and a fairl}- deep soil. All of these sources of sugar could 

 be used for fermentive purposes for the production of alcohol 

 if the necessity arose. During the war, an increased fraction 

 has been used directly as human food. Some fraction might 

 be used for the manufacture of jam. No doubt a mixture 

 of swede turnip pulp and fruit boiled down would not be 

 a first-class jam, but it would be better than letting the fruit 

 waste. Unfortunately, turnips do not ripen till after most 

 of the fruit is over, but some of the later fruits might be 

 used. Sugar beet will keep well, and could be held over the 

 winter, when it might be used for the preservation of early 

 summer truits. Sugar beet can be dried easily, and ground 

 in the mill to powder, when a crude sugar results. As 

 war measures, such schemes are worth a trial. 



(b) Starch. — Starch is chiefly produced in cereal crops, 

 although it is a common ingredient of many forms of plant 

 life. Excepting in some of the oil seeds, it may be found in 

 any of the finished forms of plant life, and is one of the food 

 reserves of the plant. The methods of preparing starch are 

 almost independent of its origin. The systems chiefly 

 employed are — 



(i) The fermentation process, in which the material, 

 after being ground up with water, is allowed to ferment. 

 The fermentation results in the solution of the albuminous 



