392 BOTANICAL GAZETTE [November 



as can be detected there is no evidence of tracheal formation. 

 Figs. 7-9 are from cuttings made on the same individual at this 

 time, but each successively nearer the ground. In the first two 

 growth is in evidence, while in the last the cambium is still in the 

 resting condition. It is evident from the photographs that in the 

 spring of 1910 growth made itself manifest in tree III as early as 

 April 15. Cuttings taken from trees IV and V at the same date 

 hkewise showed evidence of cambial activity. While there was no 

 satisfactory evidence obtained the previous year as regards cambial 

 awakening, since observations were begun too late, sections from 

 tree II on May 13, 1910, showed growth in such an advanced state 

 that cambial activity must have begun fully as early the previous 

 year. 



As regards cambial awakening in trees A, B, and C, no lengthy 

 observations were carried on; but two cuttings per tree were made 

 on April 27, one on the north side and one on the south. At this 

 date trees B and C already showed evidences of growth at breast 

 height in both cuttings. In tree A the cambium was still in the 

 resting condition. However, tree A was older and taller than the 

 other individuals, and it is very evident that growth niust have 

 already begun in the higher parts. 



The observations described above are in accord with those of 

 other investigators. Busgen (3) gives the time in general for 

 cambial awakening for middle Germany as between the last half 

 of April and the first half of May. R. Hartig (7) has observed 

 that evidences of growth arg manifest in young (10 years) specimens 

 of Pinus sihestris as early as April 20, while its appearance at the 

 base of the older trees depended very much on external factors, 

 such as thickness of stand, soil conditions, ground cover, etc. 

 BucKHOTJT (2), by means of bark measure, gives the date of growth 

 inception in larch and white pine as the last week in April. How- 

 ever, as his computations were made at the base of the trees, 

 probably growth began aloft eariier. That growth was not evi- 

 denced at the base of tree A was due, according to the researches 

 of R. Hartig (7), to at least three causes, namely {a) long trunk, 

 (&) age, and (c) shaded base. While the present investigations do 

 not afford conclusive evidence, inasmuch as they covered but a 



