LEMON 373 



orange fruits, but the seeds are rudimentary; and the taste is aro- 

 matic and bitter. 



LIMONIS CORTEX. Lemon Peel. The rind of the fresh fruit 

 of Citrus medica Limonum (Fam. Rutaceae), a tree indigenous to 

 northern India and cultivated in the European countries bordering 

 the Mediterranean, the West Indies and other tropical and sub- 

 tropical countries. The outer yellowish layer is the part used and 

 it is removed by grating. 



Description. The outer, lemon-yellow or dark yellow layer 

 recently separated by grating or paring and consisting of an epi- 

 dermal layer, numerous parenchyma cells containing yellow chromo- 

 plastids and large schizo-lysigenous oil cavities with globules of the 

 volatile oil; odor highly fragrant, distinct; taste pungently aromatic. 



Inner Structure. An epidermal layer composed of small tabular 

 cells, a hypodermal layer containing numerous plastids, a mesocarp 

 with colorless, thin-walled parenchyma and large, ellipsoidal schizo- 

 lysigenous oil cavities; parenchyma cells containing a layer of gran- 

 ular protoplasm adhering to the walls and occasionally membrane 

 crystals of calcium oxalate, which are irregularly polygonal in shape, 

 polarize light strongly and from 0.015 to 0.025 mm. in diameter. 



Constituents. Volatile oil; a very small quantity of hesperidin 

 and other bitter principles (see bitter orange peel) ; a principle resem- 

 bling tannin; calcium oxalate; ash about 4 per cent. The volatile 

 oil obtained by expression from fresh lemon peel consists of 90 per 

 cent d-limonene; 7 to 10 per cent of citral, which is the most impor- 

 ant constituent; and a small quantity of citronellal, geranyl acetate, 

 terpineol, methyl heptenone, a sesquiterpene and octyl and nonyl 

 aldehydes. 



Limonis Succus, or lemon juice, consists of 5.39 to 8.30 per cent of 

 citric acid, in part free and also combined as an ester; saccharose, 

 0.52 per cent; invert sugar, 1.42 per cent; extract, 10.44 per cent; 

 nitrogenous substances, 0.32 per cent; and ash, 0.2 per cent, the 

 latter consisting chiefly of potassium and calcium phosphates. 



Casimiroa Edulis. The seeds of Casimiroa edulis (Fam. 

 Rutacese), a tree widely distributed throughout Mexico and Central 

 America. The fruit and seed of this tree are recognized by the 

 Pharmacopoeia of Mexico under the title of Zapote bianco. The 

 fruit is edible, although stated to induce sleep, whereas the kernels of 

 the seed have been regarded as deleterious or even fatal in their effects. 

 A chemical examination of the seeds showed them to contain a num- 

 ber of interesting compounds; two new, crystalline alkaloids, one of 

 the latter having been designated as casimiroine, and the other casi- 



