364 CHENOPODIACE^ 



inches asunder in the row. As the young plants are very 

 susceptible to frost the seed should not be sown before about 

 the middle of April or the beginning of May. The amount 

 of seed necessary to drill an acre is about 30 lbs. : it is usually 

 soaked in water for 24 hours before sowing, and should not be 

 buried more than an inch deep. 



Harvesting. — The vegetative period necessary for the satis- 

 factory production of a 'ripe' root is from 140 to 150 days in 

 England, so that if sown at the proper time the crop is usually 

 ready to be harvested from about the middle to the end of 

 September, at which time the roots are dug up with a narrow 

 spade or a two-pronged fork. 



Yield. — The yield is usually from 12 to 16 t6ns per acre. 



Composition. — The water-content of a sugar beet is about 

 82 per cent. The amount of cane sugar present averages 15 

 or 1 6 per cent, in good varieties; the woody fibre about 1.3 

 per cent. 



Ex. 184. — Germinate some mangel 'seeds' in damp sand. Find out how 

 the root escapes from the fruit. 



Carefully extract some of the true seeds with a strong needle or a knife, 

 and cut sections to show the curved cotyledons and endosperm. 



Ex. 185. — Examine seedling mangel plants in various stages of development, 

 paying special attention to the primary root, hypocotyl, and secondary roots. 



Ex. 186. — Cut transverse and longitudinal sections of a full grown mangel 

 'root.' Note the distribution of the vascular tissue and soft parenchyma. 

 Observe which parts are coloured pink, crimson, or yellow, and which are 

 white. 



Ex. 187. — Cut transverse sections and count thB 'rings' in large and 

 small mangel ' roots ' from the same crop. Note if the difference in total 

 diameter of the ' roots ' is due to greater width of each ring or to a greater 

 number of rings in the larger specimens. 



Ex. 188.— Examine and describe the stem, leaves, and flower of a ' bolted' 

 mangel or a normal second year plant. 



Ex. 189.— Examine a number of commercial mangel ' seeds.' Observe the 

 shrivelled tips of the perianths, and find out the number of true fruits in each 

 so-called 'seed.' 



Ex. 190.— The student should become acquainted with the chief characters 

 of the common species of Chenopodium and Atriplex. 



