428 Spalding. — On the Traumatropic 
case a small brown spot, where the tissue had been killed, 
could be seen. The radicles were allowed to grow in a damp 
atmosphere, and when examined twenty-four hours later it 
was found that in the case of those specimens branded not 
more than 1*5 mm. from the apex there was more or less 
traumatropic curvature, as shown in Fig. 2. Those branded 
more than 1*5 mm. from the apex, Figs. 3, 4, 5 (branded 
respectively 2, 2-5, and 4 mm. from the apex), showed no 
traumatropic curvature whatever. At the point of branding, 
in each case, the short mechanical bend was plainly seen. 
This is of course more conspicuous when it is far enough 
back to have considerable elongation of the root take place 
beyond it (Fig. 5), but the bend is essentially the same at 
whatever point it occurs, and whether or not traumatropic 
curvature takes place at the same time. (Compare Fig. 2, in 
which there is plain traumatropic curvature, with Figs. 3, 4, 
and 5, in which only the mechanical bend is seen.) 
Similar results have followed so uniformly and in such 
a number of experiments with radicles of different species, 
that the following general statement may be made without 
qualification: — Traumatropic curvature follows when the 
radicle is branded close to the apex, but when the branding 
is done back of a certain point, which varies somewhat in 
different species and in Vicia Faba is very near 1*5 mm. from 
the apex, no such curvature results, and only mechanical 
bending takes place. This mechanical bending, towards the 
side branded, is seen in all cases, whatever the distance of 
the brand from the apex, provided it does not lie back of the 
zone of growth. 
Incidentally attention should be directed to an effect of 
the disturbance of normal growth that is occasioned by brand- 
ing, and is manifested by the swelling of that part of the 
radicle lying back of the zone of most rapid growth. This is 
shown most clearly in Figs. 2 and 4. 
3. Similar experiments, in which nitrate of silver was 
employed instead of branding, show precisely the same 
results, with the same distinction between traumatropic and 
