434 Journal of Agricultural Research voI.xiii.no. s 



A third form of extrafloral nectary (Pi. 50, A, B) is found on the 

 underside of the principal foliar vein, not far from its base. These nec- 

 taries are shallow pits, varying considerably in shape and outline. On 

 the cotyledon no pit occurs; the nectary is represented by a small group 

 of poorly developed, nearly nonfunctional papillae on the lower surface of 

 the midvein (PI. 49, B). On the leaves of G. harhadense each of the 

 three principal veins usually possesses a nectary; that of the midvein is 

 largest and usually sagittate in outline, with the point toward the apex 

 of the leaf. 



Internal glands are frequently found in the parenchymal tissues close 

 to the nectaries (PI. 49, B; 50, A, B), especially those of the leaf; but 

 they have no organic connection with them. 



Septate papillae similar to those of the nectaries occur frequently on 

 the young green parts of the plant. 



SUMMARY 



(i) Internal glands of lysigenous formation are found in the primary 

 cortex, foliage, flower, and seed of Upland cotton {Gossypium hirsutum). 



(2) The secondary cortex contains glands of a similar type. Some of 

 these appear to be developed from the enlargement of a single cell. 



(3) The glands in portions of the plant which are exposed to light are 

 surrounded by an anthocyan-bearing envelope of flattened cells, and 

 contain quercetin, probably partly or wholly in the form of its glucosids 

 quercimeritrin or isoquercitrin, ethereal oil, resins, and perhaps tannins. 



(4) The glands not normally exposed to the light are surrounded by 

 a layer of flattened cells containing no anthocyans; they contain gossypol. 



(5) Gossypol is formed in the glands of the developing corolla; on 

 their exposure to light it is replaced by quercimeritrin. 



(6) Gossypol in the unfolding cotyledons is changed, probably through 

 oxidation, without the formation of quercimeritrin. 



(7) Internal glands of the type described are universally present 

 within Gossypium spp. 



(8) Internal glands occur to some extent within the related genera, 

 Thespesia, Cienfuegosia, Erioxylon, and Ingenhouzia. 



(9) Four types of glands which function as nectaries occur in G. 

 hirsutu7n. These differ morphologically from the internal glands and 

 have no connection with them. 



LITERATURE CITED 

 (i) Cook, O. F. 



1906. WEEVIL-RESISTING ADAPTATIONS OF THE COTTON PLANT. U. S. Dept. AgT. 



Bur. Plant Indus. Bui. 88, 87 p., 10 pi. 

 (2) DUMONT, A. 



1887. RECHERCHES SUR l'anatomie compar^E des malvacjSes; bombaciIes, 

 ULIace;es, sterculiac^es. In Ann. Sci. Nat., Bot., s. 7, t. 6, p. 

 129-246, pi. 4-7. 



