262 BOTANICAL GAZETTE [SEPTEMBER 
details of the experiments which I have made with various contrivances. 
It is sufficient to say that I have never detected the slightest influence 
of any description detrimental to the normal growth of the root on 
account of its use. The apparatus consists of a simple hand balance 
with a light straw attached to one arm and a metal rod to the other.’ 
The lower end of this rod has a metal disk attached to it and is sus- 
pended ina beaker of water. The root is fastened securely by pin- 
ning the seed to a cork (a) held by aclamp. Surrounding the lower 
end of the root is a harness which eliminates all curvatures and keeps 
the root straight. The lower end of the harness is in direct contact 
with the disk, and every increment of growth of the root in length 
causes a corresponding depression of the balance arm, which move- 
ment is multiplied and registered by means of the straw on a recording 
cylinder. The details of the harness are shown in cuts /, 2, andj. 
It consists of six long nickel plated wires, such as are used for insect 
pins. These are passed at equal distances from each other through a 
piece of cork (f) 5™™ in diameter. They are not passed vertically 
through the cork, but spread at the top as shown in /. Another 
smaller piece (%) has a circular hole provided with grooves for the pins, 
and enables them to be adjusted to the root. By sliding the cork up 
the wires are brought into close contact with the root and by sliding 
down the root is released. It is necessary that the harness should va 
clasp the root too tightly, but just fit easily. The harness figured 18 
made for Vicia Faba, and it would not be advisable to use it for ai 
species. A delicate mechanism, however, could be constructed entirely 
out of metal which could be adjusted to any root. With the ham 
balance as a multiplying agent I have never used a weight for the root 
to overcome which exceeded 5o™. As the straw does not pass through 
a vertical line in its movements, there is a slight error in registerInos 
but it is so minute that it need not be considered, as for every oi 
meter’s growth of the root in length the error in our apparatus woul 
equal but 445". The same multiplying apparatus can be used re 
for measuring the growth of the cotyledons in grasses, in which wee 
a paper cylinder is placed around the cotyledon to eliminate the mee 
of light. By applying the harness to the cotyledon, the power 
growth can also be obtained. ee 
Nutating apparatus (/. X, fig. ¢).—This instrument is simil 
that recommended by Wiesner, who has justly criticised the me 
2 Of. Bot. Gaz, 17:105. 1892. 
ar '0 
