48 



HUTCHINSON'S POPULAR BOTANY 



m = <;. 



cherry, red whortleberry, and the " hip " of the Dog-rose (fig. 67) ; and it 

 exists, with an equal proportion of another acid malic in the cells of 

 the red gooseberry, the currant, the bilberry, the black cherry, the wood 

 strawberry, and the raspberry (lig. 68) ; while the latter is found alone in 

 apples, pears, etc. As these acids are much disliked by birds and mammals, 

 they serve as a protection to the young fruit, which would otherwise 

 get eaten before the seeds are ripe and ready for dispersion. As the seeds 



mature, however, a 

 sweetening property is 

 added to the sap, and 

 so the visits of birds 

 and other fruit-eating 

 animals, whose presence 

 is now required, are 

 bountifully encouraged. 

 The acid juice of 

 Gymnema sylvestre, a 

 tropical Asclepiad, des- 

 troys or vitiates the 

 taste if the leaves be 

 chewed. Mr. Edge- 

 worth, who was the first 

 to draw attention to 

 this singular fact, states 

 that " after masticating 

 the leaf, powdered sugar 

 was like sand in the 

 mouth ; while a sweet 

 orange had the flavour 

 of a sour lime, the sour- 

 ness of the citric acid 

 being alone distinguish- 

 able. Only sweet and 

 bitter flavours are thus 

 destroyed. This indi- 

 cates that the action is not due to a complete temporary paralysis of the 

 nerves of taste. After a good dose of the leaf, sulphate of quinine tastes 

 like chalk. The effect usually lasts two or three hours." It has been 

 proposed to call the acid Gymnaic acid, after the plant. 



The sweet pink cell-sap of the Common Beet (Beta vulgaris, fig. 70) 

 owes its sweetness to the presence of Canose (cane-sugar) dissolved in it. 

 The Prussian chemist Margraff was the first to discover this fact (about 

 1747), but it was not till the year 1809, when Napoleon forbade the importa- 

 tion of West Indian cane-sugar into France, that the discovery was turned 



[E. Step. 



Pholo by] 



FIG. 73. CHICORY (Cichorium intybus). 

 A Composite plant with flowers of a distinctive bright blue . Its thick roots contain 



Itiuhn. EUROPE, N. AFRICA, N.W. INDIA 



