May 20. 1918 Chemistry and Histology of Glands of Cotton 429 



Other substances doubtless occur within the internal glands. A resin 

 reaction is obtained by prolonged treatment with copper acetate. Pro- 

 longed treatment with chromic-acid reagents results in the conversion of 

 apparently the whole content of the glands not exposed to light into a re- 

 sinous-brown solid which is insoluble in water and alcohol and which gives 

 the sulphuric-acid red reaction slowly, or not at all. The contents of those 

 exposed to light form a yellow or dark-brown precipitate upon the walls 

 of the cavity. This property of precipitation with chromic acid indicates 

 that some of the contents of the glands may be closely allied to tannin. 



Vanillin-hydrochloric acid gives, after several minutes, a strong 

 phloroglucin reaction within the glands of the seed and root. None has 

 been noted within the glands of the other parts, but phloroglucin is 

 present within the adjoining cells. Sugar is frequently present in the 

 glands exposed to light. Positive tests are given with a-napthol, sul- 

 phuric acid, and alkaline copper tartrate. The presence of sugar is 

 somewhat doubtful in the other glands. 



PRESENCE OF FI.AVONE SUBSTANCES OUTSIDE GLANDS 



In the green parts flavones are found only in the gland secretion. In 

 the roots they occur in the outside cortical layers. They give the 

 gossypol-red reaction and also a strong precipitation with tannin reagents. 

 Pollen grains are colored bright red by sulphuric acid; those of Malva 

 silvesiris L- show a similar reaction. Flavones which agree with those of 

 the green parts in forming a yellow solution with sulphuric acid occur 

 in the seed, largely in the palisade layers of the cotyledons. Similar 

 substances give the yellow coloration to the petals of G. barbadense, and 

 are foimd to a less extent in the unfolding, nearly colorless or yellow 

 corollas of G hirsutum, being later obscured by anthocyans; but they are 

 still capable of being shown by reagents. It is probable that the flavones 

 in the glands form but a small proportion of the total amount present in 

 the corolla. 



RELATIONSHIP BETWEEN GOSSYPOL AND QUERCETIN AND ITS GLUCOSIDS 



Marchlewski (7) terms gossypol a "dihydroxy phenolic substance," 

 and proposes for it the formula Ciglli^O^, with CajHg^Oio as an alternate 

 formula. Withers and Carruth (/p) consider that Marchlewski 's sub- 

 stance contained acetic acid in combination. Their paper, which dis- 

 cusses the physiological efifect of gossypol, does not deal extensively 

 with the chemistry of the substance. They are now preparing pub- 

 lications which, it is to be hoped, will clear up the uncertainty v/hich at 

 present exists regarding the composition of gossypol. In the present 

 state of our knowledge the exact chemical relation of gossypol to quer- 

 cetin and its glucosids is uncertain. Perkin (9), referring to the work 

 of Marchlewski on gossypol, states: 



It [gossypol] . . . does not appear to be closely allied with that (dye) present 

 in the flowers. 



