THE PROTOPLAST AS HOUSE-BUILDER 



53 



FIG. 78. CRYSTALLOIDS AND 



GLOBOIDS IN ALEURONE 



GRAINS. 



leaf, and letting themselves fall from thence to 

 the ground. Some succeeded, but others tried 

 this method of escape too late ; for the air sdon 

 hardened the milky juice into a tough brown 

 substance, and after this all the strugglings of 

 the ants to free themselves from the viscid 

 matter were in vain. Their movements became 

 gradually fewer and weaker, until finally they 

 ceased altogether." 



Latex-yielding plants increase in number as 

 we approach the tropics. The milk-sap is in 



some cases extremely nutritious ; but mostly poisonous in the highest 

 degree. The juice of one species of Euphorbia (E. balsamifera^ thickened 

 into a jelly, is eaten as a delicacy by the inhabitants of the Canary Islands ; 

 and the Singhalese use the latex of the Ceylon Cow- 

 tree (Gymnema lactiferum) exactly as we do milk a 

 fact which perhaps accounts for what Miss Gordon 

 Gumming calls their "invincible objection to cow's 

 milk." * The South Americans have their Cow-tree 

 also (Galactodendron utile), a native of Venezuela, 

 where it forms large forests. If a tolerably large 

 incision be made in the trunk of one of these trees, 

 it will yield a quantity of rich sweet milk, sufficient 

 to satisfy the hunger of several persons. " What 

 most interested us " (in the virgin forest near Para), 

 says Dr. Wallace in his Travels on the Amazon, " were 

 several large logs of the Milk-tree. On our way 

 through the forest we had seen some trunks much 

 notched by persons who had been extracting the milk. It is one of the 

 noblest trees of the forest, rising with a straight stem to an enormous 

 height. The timber is very hard, fine grained, and durable ; and is valu- 

 able for works which are much exposed to the weather. The fruit is eatable 

 and very good, the size of a small apple and full of a rich and very juicy 

 pulp. But strangest of all is the vegetable milk, which exudes in abundance 

 when the bark is cut. It has about the consistence 

 of thick cream, and but for a very slight peculiar 

 taste could scarcely be distinguished from the 

 genuine product of the cow." Some notches 



* " This prejudice has been in a measure conquered in the 

 immediate neighbourhood of towns where foreigners require a 

 regular supply ; but (like the Chinese) no Singhalese man, 

 woman, or child seems ever to drink cow's milk, though a 

 little is occasionally used in the form of curds and eaten 



with ghee, which is a sort of rancid butter." Two Happy FIG. 80. CRYSTALS IN CELLS 

 Years in Ceylon, by C. F. Gordon Gumming, vol. i. p. 113. OF ONION (Allium). 



FIG. 79. AN OLIVE WITH 

 PART OF THE FLESH RE- 

 MOVED TO SHOW THE 



STONY CENTRE. 



