Nov. IS. 191S Gossypol, the Toxic Substance in Cottonseed Meal 281 



Guinea pig B. — In perfectly normal health at the end of first feeding period. Died 

 in second experiment, showing much irritation in intestines. 



Rabbit 960. — Broke its back accidentally and was chloroformed. Its case is of 

 interest in that the autopsy showed no pathological lesions in the time usually required 

 to kill an animal with cottonseed meal. 



Rabbits 969 and 970.— Had previously been on the alcoholic extract (feed 330) for 

 26 days without ill effects. 



ARE THE BAD EFFECTS OF FEED 316 DUE TO GOSSYPOI< ? 



Feed 316 is of a pale-yellow color. Moistened with ether and exam- 

 ined through a lens, numerous black specks are seen, as in the unex- 

 tracted kernels. These represent the gossypol glands, the contents of 

 which have in part been removed by ether. Sometimes these glands 

 have become separated from the seed tissue and can be examined indi- 

 vidually. They dissolve in concentrated sulphuric acid with a red color, 

 indicating gossypol. On warming a gram or so of the extracted kernels 

 with alcoholic potash and shaking, a darkening in shade with a sugges- 

 tion of a purple color takes jolace in the supernatant liquid. This is 

 characteristic of gossypol, the depth of color depending upon the amount 

 of gossypol. When the alcoholic alkali first touches the particles, they 

 turn several shades deeper to a yellow that matches the color of cotton- 

 seed meal very closely. This is also characteristic of gossypol. On the 

 addition of acid the former light-yellow color returns. 



If the extracted kernels are allowed to soak in water for a short while, 

 a substance dissolves which gives the liquid a reddish violet color. This 

 is probably due to an oxidation product of gossypol. The coloration is 

 quite permanent.^ 



These experiments show that gossypol or oxidation products of gossypol 

 or possibly other similar substances (see Power and Browning, 1 914, p. 420) 

 are still present in this residue after the long-continued ether extraction. 



The fact that gossypol is not completely extracted by ether, although 

 very soluble in it, may be due to its being held mechanically in imper- 

 vious cells, being fixed dye like in the tissue, or being in the form of an 

 insoluble metallic salt. 



Therefore, it seems to us that even the slight toxicity of the residue 

 after ether extraction is due to its gossypol content. (See data on 

 rabbit 978, Table VII, p. 276.) 



TOXICITY OF KERNELS PRACTICAIvLY GOSSYPOL-FREE 



Ether- Alcohol-Extracted Kernels (Feed 331) 



In order to determine whether it were possible by extraction with 

 solvents to prepare a cottonseed feed which would not produce any bad 

 results with rabbits, the ground kernels were extracted first with gaso- 

 line to remove oil, etc., then with ether in a large separatory funnel 

 until the percolate was of a very faint-yellow color. The residue was 



1 An attempt will be made to correlate this observation with the red sap (anthocyan?) of certain species 

 of Gossypium. 



