gi 
MacDouGaL: SoME CORRELATIONS OF LEAVES 511 
Lamium Orvala, Aconitum Stoerkianum, Clematis Vitalba, Syringa 
vulgaris, Corylus Avellana atropurpurea, Gillenia trifoliata, Prunus 
Mahaleb, Aesculus Hippocastanum, Ampelopsis hederacea, Aristo- 
lochia Sipho, Acer platanoides, Rosa centifolia and Phaseolus multi- 
fiorus.* In addition to results previously cited, Braun concludes 
also that the effect of delamination is to increase the photosyn- 
thetic capacity of stems, retard the development of internodes and 
interrupt the formation of woody tissue, all of which is confirmed 
by my own results. Braun also suggests that the condition of 
delaminated stems may be regarded as pathological, and that it is 
directly due to mechanical interferences with the functions 
involved. The condition of delaminated branches is undoubtedly 
one of hypoplasia, but a careful consideration of the various fea- 
tures involved leaves but little doubt that the failure to develop 
is largely due to the absence of the customary stimuli in response 
to which the several tissues carry on growth and differentiation in 
anormal manner. The results in question are quite as much a 
matter of correlation dependent upon stimulative factors, as the 
variations in position and growth in compound leaves as discovered 
by Zeleny. 
The more important facts observed as a result of cutting away 
the laminae of the leaves of Acer and Prunus by severing the 
petiole near the base may be briefly summarized as follows : 
I. The duration of the stipules of Prunus is increased, so that 
ten pairs of these organs are to be found on branches at a time 
when only two or three pairs are present on a normal branch. 
II. The stipular surfaces exposed on delaminated branches of 
Prunus were sixteen times as great as on normal branches. 
III. The individual stipules of Praxws were of a maximum 
measurement in length and width on the delaminated branches and 
were much larger than the stipules present on the corresponding 
part of normal branches. : 
IV. The position of the stipules of Prunus on delaminated 
leaves was more divergent than the normal, and approximated 
that of a typical leaf. 
V. The structure of the stipules of Prunus was modified in 
*Braun, A. Ueber Veranderungen im Gewebe entlaubter Stengel und Zweige. 
(Inaug. Diss. ) Erlangen. 1899. 
