978 KNUDSON: CAMBIUM DEVELOPMENT IN AMERICAN LARCH 
to June 3 the growth was markedly increased, while from June 3 
to June 15 seemingly little growth occurred. After June 3 it 
appears that relatively few new phloem cells were formed, but 
growth consisted more of an enlargement of the cells already 
formed. Some of. the figures for June 15 are less than the corres- 
ponding figures for June 3. This may be perhaps explained by 
the fact that the cuttings were made somewhat lower, or better 
perhaps by the fact that in obtaining these cuttings they were not 
taken on a line directly below the preceding, but to one side. 
Mer (loc. cit.) draws special attention to the well-known obser- 
vation that wood growth is not always uniform on all sides of the 
tree. 
rH 
PreMed 
aad 
cee etait 
4 Sagessesas 
Cutting. 
DiacraMi. Diameter of cambium and new phloem at various different dates. 
A, Nov. 13; B, April 19; C, May 25; D, June 3. 
