130 The Microscope. 



grown in Canada and in the northwestern territories is preferred as 

 being richer in oil. 



The flax seed is hard, smooth, flattened, of a reddish brown 

 color, averaging, when plump, about 5 mm. long, by 2.5 mm. wide 

 and 1.2 mm. thick, thinner and beaked at the hilum (Fig. 1), usually 

 with a white or lighter colored edge. Owing to its shape and 

 smoothness, the seed is slippery and unstable in mass, and when 

 stored in bulk, exerts a greater lateral pressure than any other grain, 

 and hence requires storehouses for holding it to be very strongly 

 built and tied. Although seeming so hard and smooth, the seed is 

 in fact not microscopically smooth, and is very pervious to moisture. 

 Viewed as an opaque object, the seed is seen to be covered with very 

 shallow concave pits, giving the surface exactly the appearance of 

 the hammered sheet metal so much in use for ornamental purposes. 

 (Fig.l, a.) This appearance is caused by the sinking in of the outer 

 wall of the surface cells, the partition walls of which form the boun- 

 daries of the pits. An attempt to delineate this appearance, more 

 highly magnified, is made in Fig. 2. On applying water to the seed, 

 the outer cells are seen to quickly swell up, the partition walls rup- 

 ture, and vesicles, many times larger than a dozen of the original 

 cells, cover the surface ; the water, on drying, leaves a gummy 

 deposit, and the seed is left rougher and less glossy. (Fig. 3.) 



Contrary to usual experience, the structure of the seed in this 

 case cannot be so well made out from sections as by other means, the 

 testa being so hard and brittle that suitable sections cannot be made, 

 but by studying sections of the dry seed in various fluids, and by 

 acting upon the seeds and sections with various re-agents, the struc- 

 ture may be ultimately made out. A thin section from the outer 

 surface, examined in turpentine, appears as in Fig. 3. A transverse 

 section of the seed, in the same fluid, shows the testa to be com- 

 posed of two coats (Fig. 4), an outer thick, yellow layer, and an 

 inner thin, bright red layer, closely adherent to the cotyledons, 

 which are composed of regular, compressed, thin-walled cells, filled 

 with oil drops (Fig. 4, a), and some minute granules of starch. But 

 little of the structure of the outer coat can be made out in turpen- 

 tine; it much resembles muscular fibres, but at thin edges of frac- 

 tures, shows projecting cells pitted with minute perforations, as 

 shown at a. Fig. 8. The inner coat, however, is seen to be com- 

 posed of thin, flattened, solid, red blocks, some of which will be 

 found lying separate (Fig. 5, a), mostly quadrangular and strongly 

 resembling in appearance uric acid crystals. These are arranged in 



