CHEMISTRY AND HISTOLOGY OF THE GLANDS OF THE 

 COTTON PLANT, WITH NOTES ON THE OCCURRENCE 

 OF SIMILAR GLANDS IN RELATED PLANTS ^ 



By Ernest E. Stanford, Scientific Assistant, and Arno Viehoever, Pharmacog- 

 nosist in Charge, Pharmacognosy Laboratory, Bureau of Chemistry, United States 

 Department of Agriculture 



INTRODUCTION 



The work herein reported forms a portion of a chemical and biological 

 investigation of the cotton plant {Gossypium spp.), the purpose of which 

 is to isolate and determine the substance or substances which attract the 

 boll weevil. A previous paper (77) ^ discusses the isolation of certain 

 %lucosids and the products of their hydrolysis, as well as preliminary 

 studies of an ethereal oil which manifested some attraction for the boll 

 weevil. Both the glucosids and this oil, as well as several other sub- 

 stances, are largely localized in prominent internal glands which are very 

 numerous in nearly all parts of the cotton plant. The main purpose of 

 this paper is to discuss the occurrence, formation, structure, and con- 

 tents of these glands. 



Glands of another type, more properly referred to as "nectaries," 

 also occur in the cotton plant. These are superficial in position and 

 definitely localized. The internal glands have nothing in common with 

 these nectaries save the function of secretion. In certain taxonomic and 

 other literature, however, either or both types are referred to indis- 

 criminately simply as "glands." Therefore, it seems advisable also to 

 discuss briefly in this paper the nature and occurrence of the nectaries, 

 in order to distinguish them clearly from the internal secretory organs, 

 which form the main subject of the present study. 



I.— THE INTERNAL GLANDS 



The internal gland of cotton consists of an oblate or spheroidal central 

 sac 100 to 300 IX in diameter, filled with a more or less homogenous 

 yellow or brownish secretion, surrounded by an envelope of one or more 

 layers of flattened cells, which in the glands exposed to hght contain a 

 red pigment. 



DISTRIBUTION OF INTERNAL GLANDS 



Because of their dark color, which renders them plainly evident beneath 

 the epidermis of the green stem or palisade layer of the foliage, and because 

 of the supposed nature of their content, the internal glands have been 



1 Second paper of a series on the chemistry of the cotton plant, with special reference to Upland 

 cotton. 



2 Reference is made by number (italic) to "Literature cited," p. 434-435. 



Journal of Agricultural Research, Vol. XIII, No. 8 



Washington, D. C. I^Iay 2°' '9'* 



nl (419) KeyNo. E-9 



