8 Wisconsin Academy of Sciences, Arts, and Letters. 
cases root growth may precede the growth of aerial parts of trees 
in spring. 
Schwarz 19 found that radial growth may start in spring in 
various parts of trees depending on the environment. In case of 
a much shaded or overtopped tree it was found that radial 
growth had begun at the base, while half way up the trunk the 
cambium was still .dormant. In another instance 43% of the 
ring had formed at the base of a tree by July 27, while 5.5 m. up 
the trunk no growth had yet occurred. These irregularities are 
held not to be attributable to differences in temperature occurring 
at the different regions. Mechanical stimuli to be discussed 
later are held to be the instigators and distributors of radial 
growth. 
THE RELATION OF FOOD DISTRIBUTION AND THE PRESENCE OF 
ELONGATING STRUCTURES TO THE OCCURRENCE OF RADIAL 
GROWTH. 
It is of interest to know definitely what relation exists between 
the occurrence of radial growth and elongation growth or 
whether both are simply dependent upon the presence of certain 
unknown amounts of elaborated and inorganic foods in connec¬ 
tion with the enzymes that may be involved in food transforma¬ 
tions and growth. The experiments of Jost 20 indicate that a cas¬ 
ual relation exists between radial growth and some phases of elon¬ 
gation growth or the presence of unfolding buds, since on the re¬ 
moval of the buds from seedling beans radial growth practically 
ceased although elongation might continue. Starch was present in 
abundance and increased after the operation yet cambial activ¬ 
ity remained in abeyance. All the elongation buds were re¬ 
moved from several years growth of branches of Finns Laricio 
on March 8 while the dwarf branches and their leaves were al¬ 
lowed to stay. The dwarf branches w r hich were nearly terminal 
then developed elongation buds. By the end of May but few 
tracheids had developed in the decapitated branches while in 
normal branches a new layer of about twelve tracheids was pres¬ 
ent, and they had become lignified. A month later the mutilated 
19 Schwarz, F. Physiologische Untersuchungen fiber Dickenwachstum 
and Holzqualitat von Pinus silvestris. Berlin. 1899. pp. 371. 
50 Jost, L. Ueber Dickenwachstum and Jahresringbildung. Bot. 
Zeit. 49:485-95; 501-10; 525-31; 541-47; 557-63; 573-79; 589-96; 
605-11; 625-30. 1891. 
