CHEMICAL BASIS OF CORRELATION’ 
I. PRODUCTION OF EQUAL MASSES OF SHOOTS BY EQUAL 
MASSES OF SISTER LEAVES IN BRYOPHYLLUM 
CALYCINUM 
JACQUES LOEB 
(WITH EIGHTEEN FIGURES) 
In this paper the term correlation will signify the inhibiting 
influence which the growing buds of a leaf of Bryophyllum calycinum 
have upon the growth of other buds of the same leaf. It is generally 
‘known that in a complex organism the growth in one organ of the 
complex may. inhibit the growth in other organs of the same 
complex. 
In former papers? the writer has shown that when in Bryo- 
phylium calycinum one organ inhibits the growth of buds in another 
organ the inhibited organ contributes in some cases material to the 
growth in the inhibiting organ. It was known through the experi- 
ments of WAKKER and DEVrIEs' that if a piece of stem is left at- 
tached to a leaf of Bryophyllum the stem will inhibit the growth of 
shoots in the notches of the leaf, while such shoots will grow if the 
leaf is entirely isolated from the stem. The writer was able to show 
that in such a case the leaf accelerates the growth of a shoot in the 
stem attached to the leaf. Thus figs. 1 and 2 are sister leaves, that 
is, leaves from the same node of a stem of Bryophyllum. Both are 
dipping with their tips in water.4 Leaf 1, without a stem, has 
formed a shoot in 22 days, while the sister leaf in fig. 2 has formed no 
shoot, due to the inhibiting effect of the piece of stem attached to 
the leaf. The latter has accelerated the growth of the shoot in the 
piece of stem attached to the leaf, however, for a piece of stem of 
* From the Laboratories of The Rockefeller Institute for Medical Research. 
? Logs, J., Bot. Gaz. 60:249. 1915; 62:293. 1916; ene 41:704. 1915; The 
organism as a whole, p. 153. Putnam’s Sons, New York. 1916. 
3 DeVries, H., Jahrb. Wiss. Bot. 22:35. 1890-91. 
4 The result is the same when the leaves are suspended in moist air instead of 
dipping into water. 
Botanical Gazette, vol. 65] [x50 
