138 SEEDS. 



(70) Nux Vomica. 



The seeds of Strychnos Nux-vomica,'Linn. (N.O. Loganiacese) 

 The seed-coat is very thin, and consists simply of an epider- 

 mis, the cells of which have developed into hairs, below 

 which there is a narrow layer of brown, collapsed parenchyma. 

 The cells of the latter are thin walled ; in surface view they 

 appear polygonal (ti), but in profile they are so much collapsed 

 as scarcely to allow the lumen to be detected. 



The hairs which form the greater and more important part of 

 the seed-coat are of very remarkable structure. The base of each 

 is very thick walled, and often bears protuberances from the 

 lower portion which fit into corresponding depressions in the 

 neighbouring hair-base. It is marked with oblique pits, and 

 passes above into a long tubular hair, which is bent nearly at 

 right angles at a short distance from the base, so that the upper 

 part of the hair lies nearly parallel to the surface of the seed. 

 This upper part bears longitudinal rod-like thickenings, separ- 

 ated by narrow intervening thin-walled portions. These hairs 

 are arranged in the same direction viz., radiating from the 

 centre of the seed, and impart to it its silky appearance. They 

 are abundant in powdered nux vomica, but during the process of 

 pulverisation the base becomes separated, and the upper por- 

 tion is split into rod-like fragments by the fracture of the inter- 

 vening thin portions of cell- wall. 



The epidermis of the endosperm is composed of radially 

 elongated cells with moderately thick walls. The cells immedi- 

 ately within are rather smaller, but they gradually increase, not 

 only in size, but also in the thickness of the wall towards the 

 interior of the seed. 



The embryo is very small and forms but a very small propor- 

 tion of the powder. 



The diagnostic characters of powdered nux vomica are : 



(a) The hairs; the bases are generally intact, but the 

 prolongations are usually broken up into rod-like fragments 

 of the thickened portions. 



(b) The cells of the endosperm with very thick walls.. 



