504 MacDoucGAL: SOME CORRELATIONS OF LEAVES 
followed by the formation of new ones at places nearer the base 
of the leaf-blades.* It is evident therefore that the epipodium, or 
laminar portion of the leaf, is capable of the most diverse correla- 
tive reactions according to the structure, and adaptive, or secondary 
functions it has acquired. 
The lack of uniformity in the facts at hand suggested that a 
repetition of some of the experimental tests with additional species 
might yield results of value. To this end the author made a 
series of observations upon the effect of the removal of the epipo- 
dium and mesopodium of the leaves of one species upon the stip- 
Fic. 1. Prunus serotina. A, normal leaf, X %. B, normal stipules,  3- C, 
leat-base with enlarged stipules; the stump of the excised petiole is shown, > 3. 
ules of the hypopodium and upon the vegetative points of the 
stems from which the leaves arose. Additional observations were 
carried out on the influence of the removal of a leaf showing 
only a distinct mesopodium (petiole) and epipodium (lamina) upon 
the vegetative points of the stem and upon the development and 
differentiation of the tissues of the stem. 
A small specimen of Prunus serotina growing near the prop- 
agating houses of the New York Botanical Garden was selected 
for the first test. All of the young unfolding leaves, except those 
of one basal branch, were dissected by the excision of the petiole 
near the stipules on April 24, 1903. None of the leaves had un- 
folded on the above date. The plant was visited daily and the 
successive leaves removed in the same manner leaving the stipules 
intact. A number of the other small trees of the same species 
* Goebel, Regeneration in Plants. Bull. Torrey Club, 30: 197-205-1903: 
