12 THE AMERICAN BOTANIST 



that "If the Jews hung their harps upon it they must have been 

 Jew's-harps" as the branches are so very brittle. 



The bark of willows is stringy and tough and, as every- 

 body knows the twigs make good whistles. It contains a bitter 

 alkaloid, sal^cine, sometimes employed as a substitute for 

 quinine. The wood is soft, smooth and light and is used for 

 many purposes. 



Providence, R. I. 



Dying as an Adaptation. — More than half the plants 

 of the world are annuals ; they spring up, reach maturity, 

 flower, ripen their seeds and die, all within the space of a single 

 year. Conditions, however, were not always thus. Time was 

 when most of the plants were perennials and in the light 

 that this fact throws upon evolution, dying itself seems an 

 adaptation. The first plants undoubtedly lived in the water in 

 regions warm enough to escape injury from the cold, but the 

 ever increasing struggle with other plants for place, in time 

 drove some of the more vigorous to take up a place in the wet 

 lands and finally to spread to colder and drier regions. Here 

 the problem of how to escape the cold of winter or the drouth 

 of desert regions was encountered, and was solved by the 

 simple expedient of dying. Before dying, however, the plant 

 shut parts of itself up in its seeds so that though the individual 

 might not survive, the race is sure to do so. Of course 

 those plants that failed to form seeds and were not sturdy 

 enough to endure the winter left no descendants to carry on 

 the family line. In addition to the annuals there is also a large 

 number of plants that simulate annuals to the extent of dis- 

 appearing from the surface of the earth at the approach of cold 

 or drouth, but somewhere in the soil the living parts may be 

 found cunningly concealed in bulbs, tubers, corms and root- 

 stocks. 



