Ds 
FOLIAGE-LEAVES AND THE CHLOROPHYLL FUNCTION. 537 
Justicia, sp. 
A woody plant, 1-5 em. in diameter at the base, was divided at 
a height of 30 em. into two branches, 10, 20 em. long respec- 
tively. Both branches were growing actively, and the apex of each 
held a bud, one pair of rapidly expanding upright leaves, one pair 
of leaves of mature size in a horizontal position, and several 
pairs of leaves depending downward in the * rainfall" position 
described by Stahl. 
Effect of an Atmosphere free from CO,.—The shorter branch 
described above was introduced into the apparatus in such 
manner that the bud, the youngest pair, and the horizontal pair 
of leaves only were included. During the 17 days through 
which the single experiment with this plant was carried, the 
development of the bud and young leaves, and the existence of 
the mature leaves, exhibited no divergences from the normal, and 
after removal from the apparatus growth was continued in such 
manner that the leaves which had been enclosed were not 
distinguishable from others of the same age. 
Hibiscus Rosa-sinensis, Linn. 
The one specimen used in this experiment consisted of a 
number of woody shoots 1:5 m. in length, springing from a main 
trunk near the surface of the soil. Each shoot was furnished 
with a large number of active leaves, and the rate of growth was 
very slow. 
Effect of an Atmosphere free from CO,.—The terminal portion 
of a shoot, 4 em. in length, holding a leaf 3°5 cm. long and an 
apical bud, was sealed into the apparatus, where it remained fora 
period of 32 days. During this time several young leaves were 
unfolded, and the older one had attained a length of 6:5 cm., 
approximately equal to that of a normal leaf of the same age. 
The green colour was not so intense as in leaves in the open air. 
Comment.—Justicia and Hibiscus offer similar conditions to 
those afforded by Ficus and Æsculus, which were tested by 
Corenwinder (2). The tips of young plants of Ficus were not 
able to form perfect leaves, while older specimens of ZEsculus 
were able to do so. The great leaf-surface exposed on the 
free portion of the older plants would afford an ample supply 
of surplus material which would be available for the slowly 
developing leaves. 
