A2S Journal of Agricultural Research voi. xm, no. s 



Some discrepancies, especially in the matter of solubility, may readily 

 be noted between the gland secretions and the pure substances which, the 

 writers believe, make up their principal constituents. Two explana- 

 tions, either or both of which may be correct, may be cited in respect to 

 this point : 



(i) Quercimeritrin and gossypol may be present in the form of salts 

 whose solubilities differ from those of the pure substances. Perkin (lo) 

 believes quercimeritrin to exist in the petals of G. herbaceum in the form 

 of a potassium salt. In proof of this view he cites (a) the ready solu- 

 bility in water of the crude dyestuff from the corollas, in contrast to the 

 relative insolubility of quercimeritrin; (b) the presence of a large quantity 

 of potassium in the ash of his crude water extract ; (c) the preparation from 

 quercimeritrin of a monopotassiura salt readily soluble in water. With 

 respect to G. hirsutum, however, the writers do not find the gland secre- 

 tion to be appreciably soluble in water (though this may be due to the 

 protective action of an oil in which the flavone is dissolved. This will 

 be again referred to). Also, as previously described (77) pure querci- 

 meritrin has been prepared in this bureau directly by crystallization from 

 an alcohol extract of corollas of G. hirsutum, without the treatment with 

 lead acetate which Perkin employed with the species he investigated. 



(2) The discrepancies in question may be due to the presence in the 

 gland of other substances, especially of an ethereal oil in which the 

 dyestuffs are dissolved. This oil would protect the dyestuflfs against the 

 action of reagents immiscible with it in which the solutes are less soluble 

 (aqueous reagents). Conversely, the oil would render the dyestuffs 

 apparently more soluble in reagents which mix readily with it — ^for 

 example, ether — yet in which pure substances (quercimeritrin in the 

 case of ether) are almost or quite insoluble. While no microchemical 

 reaction has been developed which will definitely distinguish between 

 quercetin and its glucosids, previous work (77) showed the presence in 

 the corollas of a comparatively large amount of quercemeritrin, while the 

 foliage yielded much quercetin and httle quercimeritrin. It seems 

 probable, therefore, that the glands of the corolla contain principally 

 quercetin. This latter conjecture is strengthened by the sugar reaction 

 given by the glands of the green parts, which indicates a probable enzymic 

 hydrolysis. 



SieCRieTIONS MORS OR LESS COMMON TO BOTH TYPES OP INTERNAL GLANDS 



The presence of oil as a solvent of the flavone substances is indicated 

 by the appearance of the globules and their ready coloration with alkan- 

 nin, Sudan III, and osmic acid confirms this conjecture. The globules 

 are reduced to sohd form by treatment with dry heat at 100° C. or by 

 steam ; this and their ready solubility in alcohol indicate that the oil is of 

 a volatile nature. A volatile oil whose properties are now under investi- 

 gation has been prepared by the steam distillation of fresh cotton plants. 



