2j6 Kny . — On Correlation in the 
In these three last experiments it is readily observable that 
the primary shoots of Series 3 gained an advantage, as com- 
pared with those of Series 1, in the first few days ; whereas at 
the close of the experiment the shoots of Series 1 had the 
advantage as compared with those of Series 3. 
B. Experiments with Cuttings. 
As these experiments require a great deal of space and take 
a long time, I have only been able to make two with cuttings 
of Salix acuminata , Sm., and Salix purpurea , L. A third 
experiment made with cuttings of Hedera Helix gave no 
satisfactory results, inasmuch as it was begun at a time when 
the winter-buds had already begun to sprout and when, con- 
sequently, the store of reserve material was already partly 
exhausted. 
If the experiments with cuttings are to be carried on for 
several months, the method employed with the seedlings 
cannot be adopted : for cuttings suspended by wires in 
a saturated atmosphere soon become covered with mould. 
I was obliged, therefore, to adopt a mode of experimentation 
which allows the intact cuttings to be compared only with 
those whose sprouting green shoots are removed. Rooted 
cuttings are not strictly comparable with those whose develop- 
ing roots are repeatedly removed, as the former absorb 
a greater amount of liquid water. 
In view of these conditions, the following arrangements 
were made. Nine glass cylinders, of about 16 cm. clear 
diameter and of about 4-5 litres content, were taken, each 
being loosely closed by a wooden cover. In each cover 
a central and six peripheral holes were made, seven holes in 
all, at equal distances, each hole having a diameter of 
about 20 mm. 
On Feb. 7, 1894, the nine cylinders were filled with water 
nearly to the brim, and in each hole a cutting of about 27 cm. 
in length was fixed by means of wadding. The diameter of the 
cuttings varied from 9 to 15-5 mm. The length of the cuttings 
below and above the wooden cover was about the same. 
