Place in tJic Solar System. 133 



every soil, but they are also fitted to our place in 

 the solar system. There is a direct relation between 

 the cycle of growth in ordinary plants and the length 

 of the year. The different zones have indeed sea- 

 sons of very different lengths, but their plants either 

 cannot grow in other zones at all, or if they do, they 

 as a general thing still require the same conditions 

 as they had in their own locality. There is for each 

 species a proper season for the germination of the 

 seed, or for the unfolding of buds already formed; 

 a time for growth, ami a time for maturing seeds or 

 buds for the succeeding year. 



There is indeed great power of adaptation, espe- 

 cially among cultivated plants, so that they are sub- 

 servient to the artificial conditions that man can 

 bring to bear upon them. But even under artificial 

 conditions of the hot-house they have their cycle of 

 growth. Such plants of the torrid zone as seem to 

 have little annual change, show their adaptation by 

 their power to endure the climate of that region. 

 But among all the adaptations that can be pointed out, 

 not one can be mentioned that militates against the 

 statement that the plants upon the earth are adjust- 

 ed in their changes and growth to our distance 

 from the sun and our movements through the hea- 

 vens. The unfolding leaf, the bundles of fibres in 

 the trunk, and the maturing buds and fruit, all 

 know their time by the earth's position among the 

 stars. 



How strange it is, that the early frosts have power 

 to kill the full-grown leaf on our fruit and forest 



