446 Spalding. — On the Traumatropic 
this way. Yet out of ten roots thus treated, seven (probably 
eight) were deflected as usual. Again the evidence points to 
the sensitiveness of the punctum vegetationis, traumatropic 
curvature resulting in spite of most unfavourable mechanical 
conditions. 
In some respects the most striking results are those observed 
to follow artificial suspension of growth after wounding 
(experiments 16-27). Through these experiments it was 
found that roots that have been wounded may be held in 
casts for a period of several days, and that traumatropic 
curvature still takes place when they are released and growth 
is resumed. Elongation of the root is prevented while it is 
confined in the cast, but the formation of permanent tissue 
continues, and the zone of growth is gradually pushed forward 
so that at the conclusion of the period of confinement it is 
much nearer the extremity of the root. As a result of this, 
the curvature, which is still in the zone of rapid growth, is 
very near the apex. In other respects, however, it takes 
place essentially as in roots that have not been confined. 
Whatever changes, then, as the result of irritation, have taken 
place in the tissues above the injured cells, they remain 
effective until setting the root free renders curvature possible. 
Extraordinary as the case appears, however, it is only what 
might be expected if we regard the root as a living organism, 
and not simply as an aggregation of mechanical elements. 
The root is forcibly prevented from making a normal growth 
for a certain period, after which it is released and growth is 
resumed. Before confinement certain changes were artificially 
induced, in response to which curvature would have taken 
place had the root been free to grow. When, after confine- 
ment, growth again takes place the curvature follows. The 
whole course of events merely presents another, and on the 
whole a remarkable, illustration of the fact that, in some form, 
every vitally active organ responds through the reaction of 
its sensitive protoplasm to external influences, even though in 
the meantime the introduction of other and different conditions 
may greatly modify the outward expression of the reaction. 
