RHYTHMS IN PLANT LIFE 65 



good season is sometimes almost magical. Kropotkin 

 tells us that around Tobolsk the sown fields are harvest 

 fields in about two months ; and Brehm has given us a 

 graphic picture of the coming of the Siberian spring, which 

 shows a greater abruptness than in our latitude. In a 

 few days the desert is as the rose, the barren grounds of 

 the Tundra become a garden, the Steppes are covered 

 with lilies, and the silent hills shout for joy. All of which 

 would be impossible were it not that in seed and bud, 

 in rhizome and corm, there is an enormous storehouse of 

 treasure waiting as it were for a word, the " Open Sesame " 

 of sun and shower. 



But the legacy of the young plants is soon exhausted, 

 and they begin to fend for themselves. At this transition 

 there is sometimes a slight hiatus, which may be compared 

 to weaning, or perhaps more accurately, to the loss of 

 weight that occurs in mammalian offspring for a few 

 days after birth. The well-known " swooning " or waning 

 growth of the young corn at a certain stage corresponds 

 to the exhaustion of the seed-store and to the beginning 

 of entirely independent nutrition. This leads us naturally 

 to think of another feature of plant-life in Spring the 



uprush of sap. 



ASCENT OF SAP 



No fact of plant life is more important than this ascent 

 of sap, but we are far from a complete understanding 

 of it. The facts are that water, bearing mineral salts in 

 solution, passes from the soil into the roots by physical 

 osmosis modified to some extent by the facts that the cells 

 of the root are living. The inward flow is greatest in 

 Spring and least in Winter; its rapidity and pressure 

 vary within wide limits. 



The upward path is by the cells and vessels of the young 

 wood, as may be proved in a variety of ways. Thar it is 

 5 



