108 THE WINTER REST. 



and store it up in the permanent tissues, either 

 in bulbs, roots, tu})ers, stem, or green bark in the 

 fresh saplings. It is this withdrawal from the 

 foliage of the living green matter, together with 

 the important protoplasm and other vital principles, 

 that causes the beautiful tints of autumn. The 

 ordinary pigment being drawn off, other coloring 

 matters, till then unseen, or produced by chemical 

 changes connected with the withdrawal, come at 

 once into full prominence. If the vital principles 

 remained in the leaves through the winter, they 

 would be killed by the cold ; but by being stored 

 up in bulbs, or roots, or stems, they pass safely 

 through the frosty ordeal. In the case of some 

 few plants, however, such as laurel, holly, pines, 

 and yew-trees, which are evergreen, even in our 

 own climate, the leaves are very tough and leath- 

 ery, and are usually extremely glossy, the gloss 

 being due to a layer of transparent, empty cells, 

 which, as it were, glaze the leaf, and protect it 

 from cold as glass protects a hothouse. Such 

 plants may be looked upon as the vegetable 

 equivalents of robins, sparrows, hares, and foxes, 

 which manage to keep alive and fairly wakeful the 

 whole year round. On the other hand, the nu- 

 merous class of bulbous plants, of which only the 

 buried bulbs or tubers remain in winter, deeply 

 hidden underground, may be compared exactly 

 with the tortoise, the mole, the adder, and the 



