PHYSIOLOGY: /. WEB 
119 
3. It was necessary to test the validity of this law for the regeneration of 
shoots in isolated stems. The facts just mentioned suggested the method 
required to yield rational quantitative results. This method consisted in the 
measurement of the influence of the mass of a leaf attached to a piece of stem 
upon the quantity of shoot formation in the latter. In order to obtain strictly 
comparable results, it was necessary again to compare the effect of sister 
leaves, since sister leaves alone are sufficiently alike to guarantee comparable 
results. The method of procedure was as follows. Stems of Bryophyllum 
containing three nodes and one pair of leaves in the third (most basal) node 
were split longitudinally into two- halves, each half containing one leaf. One 
leaf remained intact, while the sister leaf attached to the other half of the 
stem was reduced in size by cutting away the greater part. Six whole stems 
TABLE 2 
Influence of Mass of Leaves Upon Mass of Shoots Regenerated by Leaf 
WEIGHT OF 
LEAVES 
JMBER OF 
5HOOTS 
EIGHT OF 
SHOOTS 
MILLIGRAMS OF 
SHOOTS PRO- 
DUCED PER 
GRAM OF 
LEAF 
55 
grams 
grams 
Experiment I. Dura- ( 
5 leaves, with center cut out 
7.610 
11 
0.755 
99 
tion 37 days \ 
5 sister leaves, intact 
13.800 
9 
1.405 
101 
Experiment II. Dura- ( 
7 leaves, with center cut out 
9.899 
21 
1.213 
122 
tion, 25 days \ 
7 sister leaves, intact 
16.935 
25 
1.995 
118 
Experiment III. Dura- j 
9 leaves, with center cut out 
10.522 
22 
2.292 
218 
tion, 32 days \ 
9 sister leaves, intact 
17.852 
30 
3.430 
192 
were used for one experiment. After splitting, the halved stems were sus- 
pended in an aquarium with the apices of the leaves just dipping in water. 
Each half stem formed one new shoot from the apical bud and new roots at 
the base, but regeneration started earlier in the half stems with a whole leaf 
attached than in the half stems with a leaf reduced in size. After about five 
weeks the regenerated shoots were cut off and weighed. It was found that 
the mass of the shoots regenerated in the two sets of halved stems was in exact 
proportion to the mass of the leaves attached to the stems (table 3). 
A similar law seems to hold for the root formation though this will have to 
be determined more definitely. The same law seems also to hold for other 
cases of regeneration of Bryophyllum not discussed in this note. 
We can, therefore, state that the quantity of regeneration in an isolated 
piece of an organism is under equal conditions and in equal time directly pro- 
