36 



Journal of Agricultural Research voi. xxii, no. i 



new roots were assuming a brown, mature appearance, and this made it 

 difficult to determine the margin of growth. 



- Figure 2 shows graphically tlie condition of the seedlings as to length 

 of stem and spring growth of needles and rootlets on the different dates 

 of transplanting. 



Apr £4 May I May 9 



Julijl-^ 



Maij£0 May 30 June 12 June IS June JO 

 Time of 7~ran^ p/a nilng 



Fig. 2. — I^ength of stem and spring growth of needles and rootlets of seedlings transplanted at different 



dates. 



Table I brings out the following points : 



I. Root growth began prior to April 24 during the spring of 19 14, or 

 over three weeks before visible stem gro^vth. Although not so indicated 

 by the table, it was found that the earliest visible root elongation took 

 place in the superficial soil layers, gradually progressing to deeper and 

 deeper levels as the season advanced, presumably in response to changes 

 in soil temperature. 



