4 The Use of a Simple Microscope. 



seeds after they have thus been dried will sometimes render 

 the plump ones more conspicuous. 



" Doctored " seed ranks as one of the impurities comprised 

 Avithin the first division. When scalded seed has been mixed 

 with choice varieties of turnip-seed, a practised eye will be able 

 to detect thein on carefully examining the hilum or germ of the 

 seed, which is killed by the treatment. In the case of over-year 

 turnip seed that has been " renovated " in the oven, a similar 

 examination will be likely to expose the deception. If trefoil 

 seeds have been " oiled," or shaken in a greasy bag, dust \yill 

 be found sticking to the surface (especially if a little dust be 

 shaken over them), which is not the case when they possess 

 only their own natural gloss. 



The bulk of the seed is made up of farina or starch, and 

 gluten. The latter, when soaked in cold water, swells so that 

 the grain may easily be crushed, or cut into thin slices, so as to 

 show its internal structure. The quantity of starch-cells and 

 their quality may thus be readily observed, and the quality of 

 the grain or seed judged of by its richness in starch grains. 



The embryo, which lies at the depression called the scar, 

 the spot at which growth commences, should be carefully 

 examined, as seed that has begun to sprout from damp, and has 

 then been checked, is wholly useless for sowing. The hilum 

 or scar is the spot at which it is attached to the seedpod or recep- 

 tacle, and where the nourishment enters it from the coverings or 

 seed vessel. When the seed is fully ripened, it separates of 

 itself, and a cicatrix is formed which offers a distinctive indica- 

 tion that the seed has been matured. It is also at this spot that 

 the moisture enters when the seed swells preparatory to growth, 

 and also where the first sprouts of the future plant protrude. 

 The state of this cicatrix, whether it be minute and perfect, or 

 has been enlarged and^ shrivelled, are the points to be examined, 

 and a comparison of good dry seed with some that has been 

 sprouted and then dried, will show most clearly in Avhat this 

 difference of appearance consists. 



With respect to " feeding-stuffs," it will be far more difficult 

 to obtain satisfactory results than with seeds, because these 

 substances being crushed or ground, the particles, altlwwjh 

 admitting of recognition hy a practised ei/e, do not present so 

 marked a difference. In the coarser kinds, the inagnifying lens 

 may serve to detect well-known bodies, but the medium powers 

 of the compound microscope will be needed in most cases. The 

 material if solid, as oilcake, should be broken down into 

 a coarse powder, and a portion examined both dry, as an opaque 

 object, and in water, as a semi-transparent one. A piece of oil- 

 cake broken small, and placed in a basin, should have a quantity 



