1S6 ELEMENTARY AGRICULTURAL CHEMISTRY 



tropical countries it becomes a perennial tree, growing to a 

 height of twenty or thirty feet. The plant will grow in 

 almost any soil, but does best on rich sandy soils. If culti- 

 vated the land should be cleared, ploughed deeply, and the 

 seeds planted in groups of three or four about six or eight feet 

 apart. The ground should be kept clear of weeds, and when 

 the plants are well up all but one of each group should be 

 destroyed. They usually commence to bear about four or five 

 months after sowing. The main stem may be nipped off so as 

 to favour the growth of lateral branches, and thus increase 

 the yield of seed. The spikes of seed should be gathered 

 before they are quite ripe, and dried in the sun, as the seeds 

 shoot out from the capsules when ripe. The cleaned seeds, 

 whose resemblance to a tick has given rise to the botanical 

 name of the plant, are then sent to be pressed. 



Castor oil is a valuable lubricant, and is also largely used as 

 an illuminant and for medicinal purposes. The residue after 

 separation of the oil is suitable for use as a manure. It cannot 

 well be used for feeding purposes, as it contains a poisonous 

 ingredient which is difficult to remove. In America from 15 

 to 25 bushels of seed per acre are usually obtained. The seeds 

 contain about 50 per cent, of oil. A bushel of seed usually 

 weighs about 46 lb. 



Swnflower-seed (Relianthus anyiuus). — The plant is an annual, 

 growing to a height of ten or twelve feet. It can be sown in 

 groups of four at distances of about three or four feet apart. 

 The yield of seed is about 50 bushels per acre ; and the dried 

 seeds contain about ^ per cent, of oil. Sunflower-seed is 

 employed as a poultry and cattle food, and also as a source of 

 oil, used as a substitute for olive oil. The " cake " left after 

 the expression of the oil furnishes a valuable cattle food. 



4. Fruits. — Most fruits are obtained from plants which 

 are perennial in habit, and are therefore hardly to be classed 

 with ordinary farm crops. Orchard management is a distinct 

 branch of agriculture, and reference to it would not be 



