504 



MacDougal : 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- 



A B C 



Fig. I. Primus serotina. A, normal leaf, X >2. B, normal stipules, X 3- C, 

 leal-base with enlarged stipules; the stump of the excised petiole is shown, X 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 Pnnuis 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. 



