272 TROPICAL AGRICULTURE 



the candlenut, which contains 65 per cent, of oil, while the 

 press cake contains only 5 to 8 per cent, of oil. 



The color of cottonseed oil is lighter from fresh seed than 

 from old seed. In the commercial manufacture of cottonseed 

 oil, the seed are delinted, decorticated, crushed, and pressed 

 either cold or hot, according to the purpose for which the 

 oil is to be used. The great extent of the industry in this 

 country is indicated by the fact that the United States exports 

 35,000,000 gallons of cottonseed oil annually in addition to 

 the large amount consumed at home. 



Cottonseed meal or the ground press cake which remains 

 after the oil has been pressed has long been an important 

 stock feed. Its greatest and most effective use has been found 

 in feeding dairy cows and in fattening steers. As a feed for 

 chickens, pigs, and sheep, it has been less extensively used. 

 It has long been known that cottonseed meal, when fed con- 

 tinuously in large rations, exercises a poisonous effect on pigs. 

 Much attention has been given to the study of this matter 

 and several theories have been proposed as to the cause of 

 the toxicity of cottonseed meal. It was once suspected that 

 the toxic action of the meal was due to the presence of pyro- 

 phosphoric acid under certain conditions. This theory, how- 

 ever, was later discredited. In practice it has been found 

 that if fed in small rations in combination with certain mineral 

 salts and an abundance of green feed the danger from poison- 

 ing is largely eliminated. Recently the North Carolina Ex- 

 periment Station has isolated from cottonseed an active 

 principle known as gossypol. It was shown that this substance 

 has a pronounced toxic effect and that the toxicity of the meal 

 could be overcome by subjecting the meal to any process 

 which would oxidize the gossypol. 



Soy bean oil is becoming a more and more important com- 

 mercial product. The soy bean ( Glycine hispida) is a familiar 

 legume, native of China, Indo-China, and Japan and now 

 cultivated throughout the world exceot in extremely cold cli- 



