AMERICAN INSTITUTE. 495 



spire, is broken, the sprouts next below having more light and 

 rain shoot up and rival each other for the supreme place, until 

 the one which enjoys the most natural advantages shades the 

 others, and by superior growth assumes the middle line and res- 

 tores the symmetry of the top. It is only because the centra^t 

 sprout enjoys more natural advantages that it grows faster and 

 thus forms a trunk and gives the peculiar shape to the tree, and 

 it is only because the lower boughs have been too much shaded by 

 surrounding vegetation that they have fallen oif and left the trunk 

 clear. Now, though the spruce when growing in the open plain 

 takes the pyramidal shape, either we may say to expose the 

 greatest amount of surface to the light and rain, or because the 

 lower branches enjoying the light and the rain remain thrifty, yet 

 when exposed by felling the surrounding forest it makes no 

 attempt to assume the pyramidal condition, either because there 

 are no leaf buds to be developed in its thick bark, or in order 

 to delay the casualty which is certain to destroy it sooner or later 

 by prostrating it and upturning its roots. So perfect are the 

 works of God that naturalists are in the habit of arguing in either 

 way as may be more convenient to the same end. If we add to 

 these facts the supposition that a young tree taken from a forest 

 of tall trees will grow taller when transplanted to the open plain 

 than one from more open fields, we shall have the most approved 

 theory of the origin of varieties. It all of it amounts to nothing 

 but a tendency in the plant by means of growing most where it 

 has most chance to grow, to accommodate itself as far as may be 

 to change of circumstances and a tendency in the race to accom- 

 modate itself as much more perfectly as may be to the same con- 

 ditions. 



If a tall tree of any species could be transplanted when fully 

 grown from its region of greatest development to the northern 

 region of its dwarf like phase, the modification required of it to 

 meet these new circumstances would be so 'great as to kill it out- 

 right. If not too much grown the extreme branches that required 

 the greatest circulation of sap would die and fall off and the tree 

 thus as it were assimilate the stunted condition. The same 

 happens whe trees are transplanted into unfavorable conditions, 



