IV.] CHANGES IN ROOTS DURING STORAGE 71 



seed ; when the seed is ripe the former root will be 

 found almost devoid of sugar or any other easily soluble 

 carbohydrate or nitrogenous compound, little remains 

 except fibre. During the storage of the mangold in the 

 clamp under ordinary farming conditions, the ripening 

 process proceeds during the closing months of the year ; 

 the roots are of course respiring, and losing in conse- 

 quence a little sugar, the nitrates and non-protein 

 nitrogen compounds are also being partially replaced by 

 proteins, but the loss of material is small as long as the 

 temperature remains low. As soon as the warmer 

 weather of the spring sets in, respiration increases, some 

 degradation of the cane sugar into reducing sugars 

 takes place, and with sprouting there will also be 

 change from the protein to non-protein nitrogenous 

 compounds. When mangolds are kept as late as May 

 or June, there is a very marked loss of dry matter by 

 respiration, which may amount to as much as one-third 

 of the original material, though the loss will be 

 disguised by the drying-ofif of water which simultane- 

 ously takes place, so that the stored mangold is 

 apparently as rich as ever in dry matter. 



In swede turnips the percentage of dry matter is about 

 the same as in mangolds, varying from about 10 to 13 

 or over, according to the variety, size of root, season and 

 soil, etc. ; the sugars present are different from the cane 

 sugars of the mangold, and there is also a considerable 

 proportion of a class of carbohydrates known as pectins, 

 bodies which form a mucilaginous jelly when boiled 

 with water. The changes which the swede turnip 

 undergoes on storage and when growing a second year 

 for seed are strictly similar to those taking place in the 

 mangold, the only difference being that in the forma- 

 tion of the seed a good deal of oil is built up from the 

 carbohydrates in the storage material. White turnips 



