12 THE PARSNIP CROP. 



D. pastinacella. The only mode of getting rid of these 

 caterpillars is to carefully shake the umbels over a gauze 

 net, and thus collect and destroy them. An Aphis resorts 

 to the parsnip plants in the beginning of June, to which 

 the specific name of A. pastinacce has been given; but 

 although it frequently appears in great swarms, Curtis 

 says that he never noticed them to produce any of those 

 injuries which they inflict on the carrot crops. 



Although parsnips are comparatively but little grown 

 in this country as a farm crop, their well-known feeding 

 properties, and the high estimation in which they are 

 held in other countries, where they are largely cultivated, 

 have claimed the attention of our chemists, from whose 

 investigations we are now pretty well acquainted with 

 their general composition and, agricultural value. The pro- 

 portion of top to roots may be taken at from 20 to 25 per 

 cent, at the time of harvest. The composition of the top 

 or leaves has not yet been subjected to examination; the 

 roots, however, contain from 80 to 85 per cent, of water, 

 and about 1 per cent, of ash or inorganic matter. The 

 composition of this inorganic matter has been determined 

 by Dr. Richardson as follows : 



Potash, 36-12 



Soda, 3-11 



Lime, 11-43 



Magnesia, 9'94 



Phosphoric acid, 18'66 



Sulphuric acid, 6'50 



Phosphate of Iron, 371 



Silica, 4-10 



Chloride of Sodium, 5'54 



Loss, &c., '89 



100-000 . 



The organic composition of the root has been very care- 

 fully determined by Dr. Yoelcker, who found it to contain 

 a distinct fatty oil of a bright yellow colour, without 



