420 Journal of Agricultural Research voi. xiii, no. s 



variously alluded to as "black glands," "gland-dots," "resin glands," 

 "oil glands," "gossypol glands," etc. They are constantly present and 

 definitely arranged throughout the genus Gossypium, although their 

 prominence varies in different species according to their size, proximity 

 to the surface, depth of pigmentation, and presence or absence of obscur- 

 ing hairs or tomentum. 



Within the seed (Pi. 42, A, C) the glands are found directly beneath 

 the palisade layer, into which they often project, causing a shortening 

 of the palisade cells, but usually no bulging of the surface. Here they 

 are oblate-spheroidal in form, with long axis perpendicular to the coty- 

 ledon surfaces. Their long axes frequently exceed half the width of the 

 cotyledon — that is, 100 to 200 fi. Smaller glands are also found in the 

 cortex of the radicle, covered by a few parenchymal layers. 



As the seedling develops, glands are formed profusely in the primary 

 cortex of the hypocotyl (PI. 43, A, B; 44, A, B) and sparingly in that of 

 the radicle (PI. 45, A, B). In the former they are nearly globular, and 

 in the latter much elongated. In the hypocotyl and the young stem the 

 glands occur very close to the epidermis, and often push it outward in 

 their development, appearing then like small, dark warts. Their for- 

 mation keeps pace with the development of the foliage; in the unfolded 

 cotyledons and true leaves they are located beneath the palisade layer in 

 the centers of small areas bounded by the anastomosing veins. Stipules, 

 bracteoles, and also the calyx and corolla (PI. 46, A, a, b) are glandulate, 

 the arrangement of glands being in general similar to that of the foliage, 

 though not all netted areas possess glands. Glands occur also within the 

 tissues of the anther and the staminal column (Pi. 46, A, c, d). The 

 principal veins of the bracteoles frequently appear nonglandulate, in 

 marked contradistinction to the areas between them; on inspection with 

 a hand lens, however, small glands may usually be seen upon them. 

 The veins of the calyx are nearly destitute of glands; these veins are set 

 closely together, and the glands between them therefore seem to run 

 in parallel lines. Glands occur plentifully upon the style, in rows between 

 and below the stigmas. The boll possesses relatively very large glands; 

 in G. hirsutum L. (PI- 46, B) they are beneath several cell layers, and are 

 accordingly less conspicuous than in G. harhadense L,., where they are close 

 to the surface, which is pitted above them. The glands of the green 

 parts are very nearly spherical in form. 



The secondary cortex also may contain glands of a slightly different 

 type (PL 47, A). These always occur within the expanded ends of the 

 medullary rays. The formation of glands in the secondary cortex would 

 seem to be influenced by the stimulus of light, They are rarely formed 

 in the secondary cortex of the stem (PI. 47, B) and here apparently only 

 where the outer tissues have become considerably suberized and opaque. 

 They occur, however, very plentifully in the root; several are usually 

 found in each phloem ray. 



No glands are found in the xylem or phloem proper nor in the seed coats. 



