326 Note on Certain Intumescences in Roots. 
Dr. Bayliss recorded abnormally elongated cortical cells 
(Bayliss, Annals of Botany, Vol. XXI, p. 397), in investigating the 
galvanotropism of roots. At the suggestion of the late Professor 
Hillhouse, an attempt was made to determine the nature of the 
response—whether it was due to electrical or traumatic stimulation. 
The primary roots of seedlings were injured in the following 
ways:—(i) an electric current of the order of a milliampere was 
passed through roots by direct contact of platinum electrodes ; (ii) 
an electric current was passed through soil in which seedlings were 
growing; (iii) a spark from a coil passed through the roots; (iv) 
by local application of acid, and of alkali; and, (v) by branding with 
a hot glass rod. 
In all cases the seedlings were allowed to continue growth in 
sawdust, after the production of the injury, for periods ranging 
from one to fifteen days. Sections showed that where the epi¬ 
dermal cells had been destroyed (no matter what the agent) and a 
scar had formed, the uninjured cortical cells below the scar had 
elongated towards it. The length of the hypertrophied cells was 
found to he dependent on the time allowed for their growth. 
In the experiments where roots were growing in a soil through 
which a current was passing (about a milliampere) there were no 
intumescences produced. This is probably due to the fact that the 
current did not pass through the roots, since they offer a greater 
resistance than a moist soil. Consequently there were no sudden 
chemical or thermal changes in the root and no wound. Therefore, 
there is no reason to believe that the electrical stimulation acts in 
any other way than as a traumatic stimulus. 
These intumescences resemble those in shoots in that they are 
produced in tissues which are normally quiescent, there is no active 
growth by cell-division, but an enlargement of previously full grown 
cells accompanied by amitotic nuclear division. 
The conclusions to he drawn are:—(i.) that the elongation of 
the cells is not due to electrical stimulus as such, and (ii.) that the 
growth in length is a traumatic response comparable to intumes¬ 
cences in shoots. 
Crewe, 
May 11th, 1910. 
H. V. DAVIS. 
