1 88 Chapters in Modern Botany CHAP. 



actively multiplying and expanding into a springy cushion, 

 which either foists the leaf off, or makes the attachment 

 so delicate that a gust of wind serves to snap the nar- 

 row bridge binding the living and the dead. That the 

 scar should thus have been prepared before the opera- 

 tion is one of the prettiest points of the economy of 

 woodland nature. The student may profitably collect 

 instances of the gradual evolution of this, starting from 

 the ordinary monocotyledons, in which no such adaptation 

 exists. 



Virtually dead the leaves now are, empty houses from 

 which the tenanting molecules of living matter have van- 

 ished, leaving little more than the ashes" on the hearth. 

 But these ashes how glorious ! for in yellow and orange, 

 in red and purple, the leaves shine forth, glowing in the low 

 beams of the autumn sun. 



Sometimes it is the green chlorophyll which breaks up, 

 and leaves little heaps of yellow grains which gladden our 

 eyes in golden leaves. Sometimes, on the other hand, amid 

 the flux of molecules inwards from the leaf, there appears 

 a special decomposition product a pigment of death an- 

 thocyan, which along with the acids so often present stains 

 the leaf with red, or without the acids gives us bluish- 

 purple, or along with the yellow grains above mentioned 

 shines out in bright orange. 



Then the leaves, flushed in death, fall gently from the 

 trees, or writhing and rustling in the wind, as if loath to be 

 separated, are finally wrenched off and scattered. Jt is the 

 curfew of the year, and the poets listen mournfully to " the 

 ground-whirl of the perished leaves of hope, the wind of 

 Death's imperishable wing." 



But as the species lives on while individuals die, so the 

 tree is hardly impoverished when the leaves fall from its 

 many branches. Over the broken parts the partition mem- 



