CHAPTER VI 

 THE CONDITIONS OF LIFE 



39. All activities dependent. We may imagine objects of all 

 kinds existing by themselves, but we cannot imagine them 

 doing anything except in relation to other things. The stars 

 in space influence each other in their movements, and every- 

 thing that human beings do depends upon the conditions 

 under which they live. 



In order to discover the relations of the outside conditions 

 to the activities of a living being, particularly of a plant, we 

 may begin with the characteristic changes that take place in 

 passing from winter to spring. In the winter most of the 

 plants of the preceding season are dead, and those that are 

 not dead are, with comparatively few exceptions, either bare 

 of all foliage or reduced to one of several kinds of " resting 

 states." There are roots and stems lying dormant under- 

 ground, and there are millions of seeds that look as lifeless 

 as pebbles until circumstances favorable to life activity appear. 



40. Sprouting of seeds. How is it that the seed sprouts in 

 some cases, and not in others ? Seeds of many different kinds 

 are kept in boxes or jars for months at a stretch, or even for 

 years, and there is no sign that any of them has sprouted ; 

 yet if some of the seeds are placed in the earth, many of 

 them will sprout in a few days. 



Just because the gardener or farmer places his seeds in the 

 ground, and they then sprout, we are likely to jump at the 

 conclusion that the soil somehow causes the seeds to begin 

 their active growth after their long rest. But this is not a sound 

 conclusion. The soil is a mixture of many kinds of stuff, some 

 of which may have something to do with the sprouting, and 



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