1914] THOMSON—SPUR SHOOT 379 
others can be made out on the specimen, though not in the photo- 
graph. When one examines the insertions of these needles, they 
are seen to continue the spiral series of the scales above them, which 
are more developed than usual and more than usually persistent. 
The spiral is a very low one in the case of the 3 lowest (the normal) 
needles, but comes out clearly in the supernumerary needles. In 
these, too, there is a very evident gradation in length, the leaves 
getting shorter the higher they stand on the axis. In fig. 13, for 
example, the 3 large (slightly spirally twisted) needles, though each 
is inserted at the base of a spiral series, are all about on a level. 
The other 3, however, are inserted at quite distinct levels. The 
shortest is the highest, the variation in their length being an inverse 
index of their position on the stem. This is true of the super- 
humerary needles of P. Sirobus, shown in fig. 4, though their rela- 
tive postions are not indicated. It is very noticeable in P. Jeffreyi 
that it is the spur with the supernumerary needles that proliferates 
most freely, though sometimes normal fascicles do also. 
In general, the needles of fascicles which have proliferated are 
irregularly deciduous, remaining attached for a good while usually, 
and often becoming brown and weathered. One can often detect 
spurs that have proliferated by these needles. I have seen these 
needles persisting in the Scotch pine when they had become 
separated as much as three-quarters of an inch by the expanding 
base of the branch. This forces on one’s attention the thorough- 
ness with which the secondary as well as the primary meristems 
of these fascicles have been revived, the pines in this respect show- 
ing complete agreement with the well known condition in the other 
genera of fascicle-leaved conifers, where, however, normal prolifera- 
tion is much more abundant. It is significant that normal prolif- 
eration in the pines occurs in the branch region of the stem and 
from fascicles with extra needles or in association with such fascicles. 
Only in the seedling have I ever observed that the branch aris- 
ing normally from a spur bears primary leaves. After injury, 
however, this is of quite frequent occurrence, especially on young 
Plants. The branch coming from the spur in fig. 10 of P. excelsa 
’ Though I did not see these in the young condition, I should infer that they were 
green, 
