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those most normal in type, have become determinate in the usual 
way by means of terminal scaly buds. Certain species of trees, 
however, show a remarkable uniformity regarding the casting 
off of the tips of all their branches. Thus in case of Zila 
platyphyllos, Scop., it was necessary to search for several hours 
during the last days of May, in order to secure the few specimens 
from which Fig. 7 was prepared, and all of these showed that 
another week would have witnessed the casting off also of these 
remaining tips (at @ in the figure). Our American linden, Tilia 
Americana, Linn., also shows terminal scars (Fig. 6). It must 
not be supposed however, that all the tips of branches thus cast 
off are in as advanced a stage of development as those figured in 
the case of the European linden. Thus in the case of a European 
species of elm, the cast-off tips were small, none of the internodes 
of these tips being more than a few millimeters in length. A 
terminal scar is also shown by U/mus Americana, Linn. (Fig. 8). 
Of course the time at which the casting off of the tips takes 
place varies widely in different species. Thus during the last 
week of May it was found impossible to find tips of branches in 
the case of E:sculus Hippocastanum which had not been cast off, 
where such an operation was at all probable. All remaining 
branches had terminal scaly buds already formed. Tilia platy- 
phyllos had also already cast off its tips, but three or four were 
still found in situ, although the plane of separation er joint had 
already been formed. Ulmus campestris, Linn., on the other 
hand, had lost only a third of its tips, although the plane of sepa- 
ration was becoming evident in the remainder. Catalpa speciosa 
had not yet reached a sufficiently advanced growth of its branches 
to give any indication of the future separation of its tips. 
It may be of interest in this connection to mention that quite 
a number of trees and shrubs do not cast off their tips, nor form 
terminal scaly buds, nor are they “killed back” by frosts, but 
the tips of the branches simply wither and remain attached to the 
stem. Diospyros Virginiana, Linn., has been figured as 4 645° 
of such a plant (Fig. 9). In certain shrubs this withering takes 
place in spring. 
; The casting off of the tips of branches may be looked upon 4° 
simply another solution of the problem how to secure determin- 
