1912] BROWN— PINUS RIGIDA 401 



3. Growth began in young 20-30-year old specimens of Pinus 

 rigida in the vicinity of Ithaca as early as April 15. While there 

 was no direct evidence of cambial awakening secured the previous 

 year, sections taken at a later date showed growth in such an 

 advanced state that it must have begun fully as early. 



4. In older trees cambial awakening is sometimes retarded at 

 the base where proper insolation is lacking. 



5. There is no appreciable difference in the time of cambial 

 awakening on the north and south sides of trees. 



6. Growth began first in 2o-2S-year-old specimens at some dis- 

 tance below the apical shoot, but during a period of 19 days 

 gradually spread upward imtil it reached the apex of the trees. 



7. Investigations on trees A,B, and C tend to show that growth 

 in older individuals begins first in the crown and spreads downward. 

 The time of its inception at the base varies with conditions of 

 insolation, bark, etc. 



8. Growth in the branches follows the same rule as in the main 

 axis. The time of awakening in the former is almost if not abso- 

 lutely identical with that in the latter. 



9. Growth spreads down the main axis faster than it does along 

 the lateral shoots. .; 



10. Except in the terminal shoot, growth in diameter was more 

 rapid between May 25 and Jime 6. In the terminal shoot itself 

 greatest rapidity of growth was manifested between June 6 and 

 June 15. 



11. No reliable deductions concerning cessation of cambial 

 activity can be drawn from the present investigations. 



12. The width of the complete ring decreases from apex to base; 

 the living portion of the cortex follows the reverse rule. 



13. A nimiber of peculiarities already noted by others are preva- 

 lent in mature specimens. These are (a) lessened density of wood 

 on the south side of trees, (6) irregularity of cambial awakening in 

 closely neighboring parts of the same section, {c) successive forma- 

 tion of new elements before previous ones have reached their 

 maximum size, and {d) double rings. 



Cornell University 

 Ithaca, N.Y. 



