156 DISEASES OF WHEAT. 



extremely thin scarcely visible cellular walls, which are filled exclusively with the gluten, 

 a small-grained, greasy, smutty-gray substance, approaching to yellow. Under these cells 

 of gluten lie, first, 



3. The albuminous bodies of the seed, which consist of large six-sided prismatic cells 

 (fig. 19, r), the walls of which are soft, clear as glass, and perfectly transparent; and the 

 hollow space in the ripe seed is filled with little grains of starch-meal (fig. 19, s; fig. 22). 

 These latter are round or irregularly egg-shaped, transparent and white, and consist of 

 concentric layers or peels (fig. 22) , the outer of which often bursts or springs open. Be- 

 tween the grains of amylum or starch-meal are found still smaller grains which consist 

 almost wholly of starch, and must be regarded as little grains of amylum. 



At the base of the seed below the little shield lies tlie embryo plant or germ ; but as the 

 same is scarcely ever found in the bud of wheal which is affected with brand, the con- 

 sideration of this here does not belong to the province of this essay, since no immediate 

 transforming influence can be referred to it. 



If now after the minute examination of the sound seed, we compare with it the struc- 

 ture of that which is aflfected by brand, we find that the diseased seed (fig. 4) is wholly 

 changed as well in respect to its form as to its structure. It has become shorter and thicker, 

 and not as in the sound seed tapering towards the top (fig. 16) , but increased in thickness 

 (fig. 4). On its base, or on the head, the anthers remain hanging or standing, while in 

 the sound seed they have long since fallen off. The head with the pistil (fig. 4, c) is 

 broader, and the outer skin (a) of the seed corn aflfected by brand is rougher and fine 

 punctured. 



Let a seed corn thus affected by brand be cut through horizontally, and it be examined 

 under a magnifying glass (fig. 5) , we find outwardly a simple outer skin, and internally 

 a dark black substance often approaching to violet, which is extremely fine grained and 

 greasy, gives out a foul penetrating ammoniacal smell, and on being dried falls to powder. 

 In the middle of the grain affected by brand we generally see a clearer colored square gray 

 spot, which on close examination is found to consist of the remains of the former cellular 

 texture. If now we examine more closely the particular organs of such a kernel affected 

 with brand, we find that the outer skin of the seed thus affected consists of a single stiff 

 layer of cells (fig. 21) , the cells of which in respect to their form and size resemble much 

 the outer cellular layer of the seed-skin of the sound seed (fig. 20, w) ; but their walls 

 are no longer porous, but paper-like, stiff and folded lengthwise : they are not so finely 

 colored as in the sound seed, but are of a smutty earth color. The second and third cel- 

 lular layer (fig. 19, o, p) of the sound seed, has wholly disappeared in the diseased one: 

 the same is true of the cells of gluten, of which not a single trace remains. 



On examining still more minutely the black smutty mass, which fills the space designed 

 for the albuminous bodies, we find that here and there it contains some particles of cellular 

 tissue, like the celluar tissue of the albuminous bodies, but the cells themselves are much 

 widened (fig. 6, d) and folded ; but the hollow spaces are filled with grains of brand (fig. 

 6, e). Should the brand not be fully ripe or developed, we find the cellular tissue still 



