INSECTS IN-JOEING CROP. 449 



growth. A question is raised by Mr. Curtis as to the 

 effect leaves thus injured might have upon cattle, should 

 they be used for feeding purposes. The roots of the man- 

 gold have been the means of calling attention to a new 

 British genus of Aphidse, which, from the circumstance of 

 having first been discovered there, has received the spe- 

 cific name of " Smyntlmrodes betce;" its peculiar habits, 

 however, have not yet been sufficiently studied to enable 

 us to know how far it is likely to affect our crops. In 

 the autumn, however, when from any circumstances a 

 root begins to decay, it is soon taken possession of by a 

 numerous variety of insects. Amongst these, large broods 

 may generally be seen of a small beetle called Gercyon 

 boletophagus, of which an acarus, the Uropoda wmbilica, 

 is a constant companion. 



The great economic value of beet as the basis of exten- 

 sive industries on the Continent, and the important posi- 

 tion it has acquired in the agricultural rotations of this 

 country, have caused the chemistry of the crop to be well 

 investigated, both as regards its sugar-producing arid its 

 feeding properties. The proportion of top to root varies 

 with the soil and the season. The average may be taken 

 at from 20 per cent, to 25 per cent., or one-fifth to one- 

 fourth. The proportions of water and of ash are subject 

 also to variations ; in bulky crops the proportion of water 

 would be greater and of ash less than in crops where the 

 growth was stunted and the roots small. The average 

 proportion of water in the bulbs may be taken at 86 to 

 90 per cent., and in the leaves at about 90 per cent. The 

 proportion of ash (mineral matter) in the bulbs averages 

 from 1- to 1'2 per cent., and in the leaves from 1-5 to 2- 

 per cent., the Long varieties appearing to contain rather a 

 higher percentage of ash, both in the bulbs and the leaves, 

 than the Globe varieties. 



The composition of this ash was determined by Messrs. 



