580  ROSACEZ. 
Description.—The quince resembles a pear in shape and 
-size; when ripe it is of a golden yellow colour. The kind 
commonly cultivated in Hurope is sour and astringent, but has 
an agreeable and aromatic smell. In Arabia and Persiasweet ~ 
edible quinces are grown, and are commonly offered for sale. 
In structure the quince differs from the pear-in haying numer- 
ous seeds in each cell, which cohere together by the mucila- - 
_ ginous membrane with which each seed is surrounded. The 
seeds are irregularly ovoid, flattened and three-sided from 
mutual pressure. At the lower end is the hilum, from which 
the raphe extends as a straight ridge to the opposite extremity, 
which is slightly beaked and marked with a scar indicating 
the chalaza. The testa is of a dark brown colour, and encloses ~ 
two cotyledons and a straight radicle directed towards the 
hilum. The kernel has the odour and taste of bitter almonds, 
but the testa is simply mucilaginons. 
Chemical composition.—According to the Pharmacographia — 
the mucilage of the epidermis is present in such quantity that 
‘the seed easily coagulates forty times its weight of water. By 
complete exhaustion, the seeds afford about 20 per cent. of dry 
mucilage, containing considerable quantities of calcium salts and 
albuminous matter, of which it is not easily deprived. When 
treated with nitric acid, it yields oxalic acid. After a short 
treatment with strong sulphuric acid it is coloured blue by 
iodine. Tollens and Kirchner (1874), assign to it the formula 
C'°H?9Q'*, regarding it as a compound of gum, C!2H% 
07°, and cellulose, C°H!°0%, less one molecule of water. 
Quince mucilage has but little adhesive power, and is not 
thickened by borax. That portion of it which is really in a 
state of solution, and which may be separated by filtration, is — 
precipitable by metallic salts or by alcohol. The latter preci- 
pitate after it has been dried is no longer dissolved by water 
either cold or warm. Quince mucilage is, on the whole, 
to be regarded as a soluble modification of cellulose. — 
Gans and Tollens show that quince mucilage yields furfur- — 
aldehyde on distillation with dilute sulphuric acid, indicating _ 
