94 Anatomy and Physiology. 



and checked in their growth. They harden into scales, which serve 

 as a protection for the internal ones, which being thus protected, 

 do not fully come out until the atmosphere has been warmed 

 sufficiently to enable them to become fully developed. This is 

 beautifully shown in the bud of the maple ; the outer scales are 

 short, hard, reddish, and rather hairy ; as you examine inwards, 

 they are longer and softer until you find the true leaves. So 

 different is the weather-case from the leaf, that examples of the 

 same species under different circumstances have to be shown to 

 prove that this is the real mode of their formation, and that scales 

 and hairs are in reality nothing but modified leaflets. The best 

 instance, and the one commonly shown, is that of the horse- 

 chestnut, which, in its native clime of India, unfolds its leaves 

 to the mild and genial atmosphere without any risk of such de- 

 generation being required, and is totally free from scales and 

 hair. 



There are some curious leaves at the lower part of the plate, 

 which being of no particular benefit, do not need description. 

 The green color of leaves, which is best adapted to our organs 

 of vision, is. manifestly a providential arrangement, for upon no 

 other color could we constantly rest our eyes without eventually 

 causing disease. Captain Parry tells us that his men were so 

 dazzled by the continual glare of the snows of the polar regions, 

 as to become for the most part blind ; and fatal results would 

 inevitably have ollowed had he not by meanfs of green specta- 

 cles or crape of that color worn over the eye, obviated in some 

 measure the pernicious effects. The pleasant impressions pro- 

 duced by the innumerable hues of this color have been well de- 

 scribed by Cowper : 



No tree in all the grove but has its charms, 

 Though each its kite peculiar ; paler some, 

 And of a wannish grey ; the willow such ; 

 And poplar that with silver lines his leaf; 

 And ash far stretching his umbrageous arm ; 

 Of deeper green the elm ; and deeper still, 

 Lord of the woods, the long surviving oak. 



