32 



STUDY OF NUTS MICROSCOPIC IDENTIFICATION. 



it is lacking over the larger part of the surface of the nut. It is 

 also thickened irregularly around the projecting radicle. The endo- 

 sperm is easily distinguished from the cotyledons by its white color. 

 The embryo, as usual, is of simple structure. The surface of the 

 cotyledons is covered by an epidermal layer of oblong and polygonal 

 cells seldom over 15 ^ long and usually at least half as broad (PL IV, 

 fig. 4) . This layer is not more than 10 \L thick, while the parenchyma 

 cells of the cotyledons average about 40 y. in diameter. The aleurone 

 grains are small and nearly circular in outline. They are most com- 

 monly 5 or 6 i& in diameter, with a few larger grains up to 15 [i in 

 diameter. 



CASHEW NUT. 



(Anacardium occidentale L., Family Anacardiacece. ) 



The cashew tree has the peculiarity of producing both a fruit and 

 an edible nut. The so-called fruit is in reality the enlarged fleshy, 



pear-shaped peduncle or fruit-stalk 

 which bears at its distal end the 

 fruit proper or nut, as it is more 

 commonly called. (Fig. 10.) The 

 latter is reniform, larger at the 

 basal end, of a grayish or slate 

 color, and has a hard, whitish mass 

 of tissue in the sinus, represent- 

 ing the stigmatic surface of the 

 carpel. The pericarp is of a stiff, 

 leathery texture, consisting of dense 

 epicarpal and endocarpal layers 

 separated by a thick, spongy meso- 

 carp, the cavities of which are 

 filled with an acrid, poisonous oil. 

 The composition and properties 

 of this liquid have been investi- 

 gated by various persons, whose 

 results are summarized by Basi- 

 ner. 1 It contains about 10 per 

 cent of the active principle, cardol, 



the remainder being largely an inactive, fatty acid, named ana- 

 cardie acid, besides which tannic acid and other substances are 

 present in smaller amounts. As cardol is regarded as the active 

 principle of poison ivy, Rhus radicans, it is not surprising that when 

 applied to the skin symptoms resembling those of ivy poisoning 

 should result, consisting of irritation, swelling, and an eczematose 

 eruption as described by Basiner. 2 Taken internally, it is nearly or 



FIG. 10. Cashew nut. 



1 Die Vergiftung mit Ranunkelol, Anemonin, und Cardol, Diss. 

 8 Loc. cit., pp. 46-53. 



Dorpat, 1881, pp. 38-40. 



