29 



later leaves attained their normal [)r()portions. A similar 

 irregular and interrupted growth is not infrequently seen in 

 ferns when several of the central pinn.e of the frond are 

 much reduced in size, and for similar reasons. 



In spring a vine of Ampelopsis on the north wall of a 

 building was wholly green, but where it turned a corner to 

 the east side it was a purplish brow^n. A simiUir change of 

 color was witnessed in the fall on a vine on a brick church. 

 It was scarlet on the south side wiiich had direct sunlight, 

 but green on the west. Even a change in the declination of 

 the sun under certain conditions may produce a change of 

 color. A vine on a north wall of a building had become 

 scarlet from drought and three or four hours of afternoon 

 sunlight. When the sun no longer shone upon that side, 

 the later growth of runners bore only green leaves ! More- 

 over on a building wall composed of boulders, or cobble 

 stones, the leaves on each rounded surface were colored, 

 but those in the depressions between, which were of mortar 

 and partly shaded were green. The effects of frost on Am- 

 pelopsis will be referred to farther on. 



Ampelopsis Veitchii is a very interesting plant for the 

 study of the effect of insects, drought, frost, etc., on the 

 color of leaves. 



Allusion has been made to the fact that there is a natural 

 coloration of ^s foliage common to certain species in early 

 spring, but dependent upon the amount of direct sunlight 

 which they receive. 



The foliage of the cultivated, red variety of Begonia 

 vernon growing in the shade is green, but in the sun is a 

 dark mahogan}^ color on the parts of the leaf reached by 

 the direct rays, as a side, the tip, along the midrib, or on 

 the lower surface, according to the i)osition of the leaf, 

 which has its sides naturally more or less incurved, thus 

 preventing the impact of the sun's rays upon the entire 

 surface. Varieties of purple-leaved beets and lettuce, of 

 Ampelopsis Veitchii, Canna. etc., are similarly dependent 



