CHEMISTRY OF CROP. 



187 



may be detected by the distorted appearance of the flower- 

 heads and young seed-pods. On opening them (see 

 woodcuf) the seeds will be found to be partially eaten, 

 some with only a hole in the"m, surrounded by abundance 

 of brown and white excrement ; other seeds are hollowed 

 out, and a cell formed in each of them of an oval form, 

 but irregular. In these cells is found either a fat maggot 

 or a pale ochreous pupa, which in due time reproduces 

 the original insect. The weevils at first are of a dirty 

 ochreous tint, but eventually become of a dark brown or 

 black colour. 



The chemistry of vetches has received but very little 

 attention either from our own or from continental 

 chemists. They usually contain in their natural state 

 about 80 to 82 per cent, of water, 16 to 18 per cent, of 

 extractive organic matter, and about 1*5 per cent, ot 

 mineral or inorganic matter. Their organic composition 

 is given as follows : 



The only analyses we have to refer to of the composition 

 of the inorganic matter or ash of the plant, is by Sprengel, 1 

 which, in default of any more recent one, we now give: 



Potash 35-28 



Lime, 38*33 



Magnesia, 6*35 



Peroxide of Iron, '18 



Protoxide of Manganese, '16 



Phosphoric acid, 5'49 



Sulphuric acid, 2'39 



Silica, 8'66 



Chloride of Sodium, 2'67 



1 Annales Agricolcs de Roville, tome viii. p. 209. 



100-00 



