278 
Kny.—On Correlation in the 
whereas this was not the case in Series 2 , where some of the 
main roots were still altogether unbranched. 
By March 10, there was no perceptible difference between 
Series 1 and 3 as regards the development of shoots. On 
March 28 there was a distinct difference in this respect, in 
favour of Series i, although the difference was not so marked 
as that between the roots of Series 1 and 2. In Series 1, 
the shoots had attained a maximum length of 232 mm. ; 
whereas in Series 3 the maximum length was only 185 mm. 
At the close of the experiment on April n, the difference in 
length was still more striking. 
The numerical results were as follows — 
Series 1.— Cuttings uninjured throughout the experiment : 
Length of the longest root . . .279 mm. 
Total gross weight of the roots . . 23-95 grm. 
Total dry weight of the roots . . 2-197 grm. 
Length of the longest shoot . . . 376 mm. 
Total gross weight of the shoots . . 121-1 grm. 
Total dry weight of the shoots . . 21-5 grm. 
Series 2.— Cuttings from which the shoots were repeatedly 
removed : 
Length of the longest root .... 220-5 mm. 
Total gross weight of the roots . . 4-55 grm. 
Total dry weight of the roots . . . 0-337 grm. 
Series 3.— Cuttings from which the roots were repeatedly 
removed : 
Length of the longest shoot . . . 216 mm. 
Total gross weight of the shoots . . 65-35 grm. 
Total dry weight of the shoots . . 14-7 grm. 
I do not give the details of an experiment carried out 
a year earlier with cuttings of Salix, because in that case the 
cuttings were not so carefully assorted according to their 
diameter as to ensure uniformity in the three series. It 
will suffice to say that the results agreed in all important 
points with those given above. 
