132 The Microscope. 



matically, a very oblique section, the various elements of which have 

 been drawn from a number of different preparations in their proper 

 order. The inner surface is at the left, the upper half of the figure 

 showing the appearance as each successive layer is focussed, and the 

 lower half the structure of the particular layer in focus. The outer 

 cells (g) are much swollen and thickened, and show the separation 

 of the cell- wall layers. The next layer (f) is of smaller cells, and 

 the following, or inner layer (d), of large cells, is composed of nearly 

 quadrangular cells, arranged in longitudinal series, and at some 

 points in the acid- boiled specimens, resembling mere rounded open- 

 ings in a structureless membrane, (c.) These layers of cells are 

 entirely empty, having contained mucilaginous matter only. Next 

 comes in several layers of long, narrow, dotted cells (b) , longitudinally 

 arranged, of deep yellow color, with a few minute oil globules among 

 them, and lastly, a single layer of thin, narrow, structureless cells, 

 transversely arranged, (h.) At the edges of the seed are a few longi- 

 tudinal bands of spiral vessels (Fig. 9), lying among the dotted cells 

 (a) and nearest the inner surface. The inner coat of the testa is 

 scarcely changed by boiling in water, but in nitric acid a remarkable 

 change is effected in the red blocks, which are converted into globular 

 concretions of radiating needles, closely resembling those of carbonate 

 of lime (Fig. 10), while their cellular membrane, before colorless, is 

 now a light yellow color. The cotyledon cells are swelled and soft- 

 ened, but not otherwise changed, and the starch has disappeared. 



Collating the foregoing observations, we deduce the structui'e of 

 the flax seed as follows: The cotyledons, composed of ordinary^ 

 cells, filled with an abundance of oil and considerable starch, in min- 

 ute granules, are enclosed in a hard, bi'ittle testa, of two separa- 

 ble layers, the inner of which is composed of a single layer of 

 solid, mostly quadrangular, thin, red blocks, of probably alkaloidal 

 nature, with finely serrate edges, enclosed in a correspondingly 

 serrate, cellular membrane, adherent by a mucilaginous or albumi- 

 nous stratum to the surface of the cotyledons ; and the outer layer of 

 testa, separated from the inner by a mucilaginous stratum, is com- 

 posed of a single transverse layer of thin, linear, hyaline cells, over- 

 laid by several layers of yellow, longitudinally arranged, dotted cells, 

 containing localized bands of spiral vessels and minute oil globules, 

 and enclosed in three or more layers of large, thin cells, containing 

 a very soluble mucilage and forming a shallow, pitted surface of the 

 seed when dry. 



