DISEASES OF WHEAT. 155 



If the transformation which the seed of wheat undergoes by the formation of brand be 

 examined, we find that the particles have undergone either an entire or partial transfor- 

 mation in respect to internal structure ; and without here entering on the technological 

 signification of the several parts of the seed, I shall describe the same, in a way generally 

 intelligible, and simply, as should always be done, and so pass over the head as well as 

 the pistil, since they suffer no visible change by the formation of the brand. The same 

 is true of the glumes and petals, the anthers and the spike of the ears themselves. 



The fruit or seed of the wheat viewed on the outside, consists of an elongated irregularly 

 egg-shaped body (fig. 16, f) , having on the front surface a streak or furrow lengthwise, 

 (fig. 16, k) , which bears on the point the pistil (fig. 16, i) , and the head (fig. 16, h) . 



At the bottom, we see on the back the little shield (fig. 15) containing the germ, and 

 the front side the little opening, Feusterchen (fig. 16, g) . If the seed is cut across 

 through the middle (fig, 18) , we find that it has an outer skin (fig. 18, I) , which by 

 bending inward forms the furrow lengthwise (k) . Inside of this skin are found white 

 hard transparent bodies containing starch-meal, which natural historians call the albumi- 

 nous bodies, " the albumen" of the seed (fig. 18, m) . If now we cut off as thin as possible 

 a slice perfectly transparent, in the direction already mentioned, and examine the same 

 microscopically, we find that, 



1. The skin of the seed (fig. 18, I) consists of three layers, to wit: 

 a. The outer layer (fig. 19, n) ; 



6. The middle layer (fig. 19, o) ; and 



c. The inner layer (fig. 19, p) , on which layer immediately lies a large soft cellular 

 stratum, which contains the grains of gluten (fig. 19, q) . Nearest the inside lie the amylum 

 cells, containing the starch-meal (fig. 19, r, s) . 



a. The outer layer of the seed-skin (fig. 19, n) , consists of two layers of thick-walled 

 porous cells, which stand with their longest diameter parallel to the axis of the seed, and 

 the walls of which contain slight hollows or little canals, which, in a section cut lengthwise 

 and very strongly magnified (fig. 20, w) , give to the cellular walls a form as if they were 

 formed of oblong figures. 



b. The second layer (fig. 19, o) of the seed-skin, consists of similar cells to those of the 

 first layer, only the walls of the cells are not so thick ; and the pores, which these walls 

 contain are much more distinctly (fig. 19, o) to be seen, than is the case in the cellular 

 walls of the first layer of the skin ; but the cells of this layer stand with axis of length 

 horizontally to the axis of the first cellular layer and of the seed, and therefore runs as it 

 were parallel to the outer surface of the seed. In a section lengthwise they resemble even 

 to the direction of the cells of the first layer of cells, and are nearly as large as they are 

 (fig. 20. x, x) . 



c. The third layer is extremely soft and somewhat confused. Its cells are so small, that 

 we can discern their hollows only indistinctly and in the form of mere streaks (fig. 19, p) . 



2. Directly under this cellular stratum or of the seed-skin in general, we find situated 

 the already mentioned cells of gluten (fig. 19, q) . They are large bag-formed cells, with 



