SEEDS. 113 



The officinal seeds do not, as a rule, contain any secretory 

 tissue, but instances to the contrary are by no means wanting. 

 Thus, cocoa seeds contain large mucilage cells in the seed-coat ; 

 nutmegs, black pepper, and cubebs contain numerous oil cells 

 and so on. 



Sometimes organs that accompany the seed contain principles 

 different from those present in the endosperm ; thus, mace, 

 which consists of the arillus of the nutmeg, contains amylo- 

 dextrin, a substance that is distinct both from starch and 

 aleurone grains ; the thickening at the base of colchicum seeds 

 contains starch, which cannot be detected in the endosperm. 



As the fruit consists normally of the seed surrounded by the 

 pericarp it is obvious that in addition to the characteristic 

 elements furnished by the seed itself, those derived from the 

 pericarp must also be taken into consideration. This part of 

 the fruit is by no means lacking in cells or tissues that are of 

 great value in the identification of the powder. It commonly 

 contains sclerenchymatous cells of very varying shape and 

 dimensions (cubebs), oil-cells (pepper), oil-glands (allspice), 

 laticiferous vessels (poppy), etc. The powders obtained from 

 umbelliferous fruits usually contain fragments of the vittse 

 which are easily recognised by their dark brown colour and 

 by the tapetal layer of regular polygonal cells. Hemlock fruit 

 contains no such vittse, but in that case the powder is 

 characterised by the shape of the cells in which the coniine is 

 secreted, and by this means powdered hemlock fruit can be dis- 

 tinguished from other similar fruits. The pericarp may also be 

 furnished with characteristic hairs or contain distinctive 

 crystals that may be utilised for a similar purpose. Occasion- 

 ally also the endocarp furnishes valuable diagnostic characters. 



