THE GRAIN 



left curve round and extend backwards in sinuous lines more or less 

 parallel to each other, a few on each side being continued almost to the 

 base of the scutellum (Fig. 13). 



In the young state the cells of the strands are thin- walled, but after 

 germination and growth of the young 

 plant, xylem tracheids, with lignified 

 walls and annular or spiral thickening, 

 are differentiated, and, in addition, a 

 certain proportion of the parenchyma 

 of the scutellum exhibits similar, 

 though less extensive, thickening of 

 most of its cell walls, transverse as 

 well as longitudinal. 



In the majority of wheats two 

 straight, unbranched bundles traverse 

 the coleoptile from base to apex, one 

 on each side, arranged in a plane 

 almost parallel to the face of the 

 scutellum ; in T. hermonis and Indo- 

 Abyssinian forms of T, dicoccum two 

 to four additional bundles are present in the outer half of the coleoptile 

 (Fig. 16). 





FlG. 13. Diagram of the bundles of the 

 scutellum. 



. 



FlG. 14. Transverse section of portion of scutellum ( x 105). e, Epithelium ; h, section 

 of large central bundle ; a, sections of small bundles (cf. Fig. 16). 



The rudimentary first green foliage leaf of T. vulgare usually possesses 

 eleven bundles, the second leaf seven. 



The arrangement and number of the bundles of the scutellum, coleop- 

 tile, and first and second foliage leaves arc shown in Fig. 15. 



Traced downwards, four bundles of the first foliage leaf (t\vo from 

 the right and two from the left of the midrib, Nos. 2, 4, 8, and 10) and 



