1915] BROWN—PINUS STROBUS 233 
the shoots ceases during early July, while that of the needles 
continues well into August. 
Comparative studies of the growth in length of shoots and 
needles have been made by others. WIELER (39) found, for 
example, that in the needles growth was completed in Pinus mon- 
tana at the beginning of July, in Pinus austriaca at the end of 
August, in Pinus silvestris by the end of July and the beginning 
of August, in Pinus Strobus during the course of August. Growth 
of the needles in Pinus, according to his observations, varies with 
the species. MEISSNER (22) likewise noted that growth of needles 
of a number of species of pine varied, especially that of Pinus 
silvestris. While he gives no exact date for the termination of 
growth of needles in the species, he states that growth in length 
of the terminal shoot ceased about the middle of July, and in all 
cases the growth of the needles continued later than that of the 
shoot. Whether all species of Pinus agree in this respect remains 
_ yet to be determined; white pine has proved no exception to the 
rule. 
Primary growth in underground parts 
The detection of primary growth in underground parts is in 
some species attended with obstacles which are well nigh insur- 
mountable. Often the new tissues are little or not at all differ- 
entiated from those of the preceding year, and in such cases it 
is very difficult to detect the beginning of growth in length in the 
spring. This is the case in white ash, where little coloration results, 
so that it is quite impossible to separate new and old parts of the 
root. Fortunately, in the Coniferae this does not apply, for within 
a space of 1cm. marked brown coloration appears, so that new 
growth can be detected without any difficulty. Furthermore, 
after the cessation of growth in the autumn, this brown mantle 
approaches nearer the root tip, so near in fact that one can be 
reasonably sure as to the presence of new growth. 
The first observations on root growth were made on April 26, 
1913. Roots were obtained from 3 and 4 year white pine specimens 
in the nursery. The frost had been out of the upper soil layers 
for only a short time, yet evidences of growth were to be seen in 
many of the root tips in the shape of small white translucent 
