1914] THOMSON—SPUR SHOOT 377 
developed into branches with both primary and secondary leaves. 
I have found similar proliferations on seedlings from the same plot, 
but could detect no injury except in one instance. The seedlings 
were all grown and carefully tended in the University Garden. 
Moreover, in both seedlings shown in pl. XX there are well devel- 
oped buds in all the spurs except two (the lowermost of fig. 2), 
some of which will in the ordinary course of events grow next year 
into branches. In fact, the main axis will come from one of these 
in both instances, as it has done in the plant shown in fig. 6. One 
is so much larger than the others in each case that there seems no 
doubt of its power to produce the main axis. 
On examination of older seedlings of other species, I found that 
branches had quite frequently arisen from spur shoots in certain 
plants, again not connected with any apparent injury. Among 
about 20 young plants of P. virginiana (?), several had proliferating 
spurs, and were vigorous specimens about 6 years of age. In fig. 7 
the two leaves (marked with a single line each) inclose the terminal 
axis with a rosette of lateral buds at its apex. These two leaves 
have very broad bases. Below and to the right is a lateral bud com- 
ing from a spur shoot with three leaves (marked with 2 lines each). 
Two of these are also broad, but the third is much narrower. It 
is to be noted that this species has its leaves normally in twos. 
Below this spur shoot is one with two broad leaves (marked with 
3 lines each) and a much smaller bud, below which again are spur 
shoots with smaller and smaller buds, until at the base of the shoot 
figured no trace of a bud could be discerned, even with a lens. 
During previous years certain of the branches also arose from spur 
shoots on this plant. In vigorous specimens of P. Sirobus, about 
8 years of age, chiefly from the plantation referred to before, but 
in the wild also, I have found that usually subsidiary branches 
occur below the normal whorl. These are smaller and in almost 
€very instance derived from the proliferation of a spur. One of 
them at the end of its first season’s growth is shown in fig. 8. It 
has normal secondary needles and is only one of several at the same 
node. Around the apex of the stem below the branch node, a 
number of this year’s spurs have small buds which are ready to 
develop next year into similar branches. In a few specimens of 
