378 CRUCIFER^ 



It is instructive to note that in two ' root ' crops whose water- 

 content is 87 and 92 per cent, respectively, every hundred lbs. 

 of the former contains 13 lbs. of dry substance, while too lbs. 

 of the latter yield 8 lbs. of solid substance when completely 

 dried : in other words, 20 tons of the former are equal in dry 

 weight to more than 32 tons of the latter. Differences in 

 water-content similar to these ordinarily exist between average 

 crops of swedes and white turnips, and even the same varia- 

 tions in composition have been met with in two swede crops, 

 one composed of somewhat small well-matured ' roots,' the 

 other consisting of very large immature ' show roots.' 



As the turnip 'root' matures the percentage of water in it 

 decreases, and the percentage of carbohydrates, principally 

 sugars, increases. 



The dry substance of the ' root ' also alters in composition as 

 the ripening proceeds ; in unripe roots much of the nitrogen 

 exists in the form of amides, compounds \\'hich are of little 

 nutrient value, whereas in mature roots the amides have largely 

 disappeared, being transformed into useful albuminoids. 



9. A good turnip. — The following points are important in 

 determining the value of a turnip or swede. 



(i) The yield should be high. 



(2) The feeding-quality, so far as composition is concerned, 

 should be good ; roots of high specific gravity are generally more 

 valuable in this respect than those of low specific gravity. 



(3) Their resistance to frost is to be considered. It is to 

 some extent dependent on inherent vital differences, and also to 

 the manner of growth of the 'root'; varieties which grow mainly 

 buried in the soil are usually more resistant to frost than those 

 whose ' roots ' are mainly above the surface of the soil. 



(4) Varieties which stand well out of the ground are however 

 more easily pulled up and more readily and completely consumed 

 by sheep than those deeply buried. 



(5) Turnips should have no ' neck ' and that of the swede 



