112 SEEDS. 



In two of the seeds that we have studied (Strychnos Nux 

 vomica and Strychnos Ignatii) belonging to the natural order 

 Loganiacese, the structure is very similar, even to the long 

 hairs that cover the surface of the former, but are found in 

 patches on that of the latter ; a distinction, however, is to be 

 found in the s'tructure of the bases of the hairs, and this is 

 sufficient to serve as a means of detecting the powder of either 

 seed when mixed with that of the other. 



These two seeds are also characterised by the horny nature of 

 the endosperm. The walls of the cells are very thick, and consist 

 of a modification of cellulose that swells even in cold water, 

 more easily in hot water or alkaline solutions. 



Areca nuts and nutmegs possess in addition a ruminate 

 endosperm by which their identification is facilitated. 



The nature of the substances contained in the cells of the 

 endosperm may also be utilised in the identification of the 

 powder. In many seeds, such, for instance, as those of cereal 

 grasses, these cells are filled with starch. This reserve material 

 is usually present in the form of distinct grains, but in some 

 cases, as in guarana, the grains may have been gelatinised, and 

 the starch is then in amorphous masses. Most of the officinal 

 seeds contain aleurone grains, especially those in which oil is 

 the principal reserve material. These are much more difficult 

 to identify than starch grains, and are best examined in almond 

 oil or glycerin, as water more or less rapidly disintegrates them. 

 The aleurone grains of the more important seeds have been 

 described and figured by Tschirch* and others. 



In some seeds as, for instance, those of Theobroma Cacao, starch 

 grains accompany the aleurone grains, and in such cases it is de- 

 sirable to employ a solution of iodine in iodide of potassium which 

 colours starch grains blue, but aleurone grains brownish-yellow. 

 Aleurone grains are, however, more commonly accompanied by 

 fixed oil, as in linseed, mustard seed, etc., than by starch. The 

 shape, size, and composition of these grains may sometimes be 

 utilised in the identification of a powder, especially the powders 

 of decorticated seeds, which, of course, contain but very little 

 debris of the seed-coats. Calcium oxalate crystals, for instance, 

 are not very commonly found in the aleurone grains of officinal 

 seeds, but are generally present in those of the endosperm of 

 umbelliferous fruits. 



* ' Angewandte Pflanzenanatomie,' p. 44. 



