iQisl 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 aU 

 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 Conif erae this does not apply, for within 

 a space of i cm. 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 



