974 KNUDSON: CAMBIUM DEVELOPMENT OF AMERICAN LARCH 
north or south. Trees B, C, and D were very uniform as regards 
size and form. Tree A, although of the same age, was slightly 
smaller. 
In’ order to determine the region of growth inception it was 
necessary to take material from the apex of the tree to the base. 
The larch has, at intervals, whorls of branches, the number of 
which agree approximately with the age of the tree. The trees 
used had each ten such whorls and material was removed from 
below each whorl, at different times throughout the growing 
season. Cuttings were made only from the south side of each tree. 
The first cuttings were made a few inches below each whorl of 
branches and the subsequent cuttings were made a few inches 
below the preceding and a little to one side. In obtaining the 
material for study two incisions, 2 cm. apart, were made through 
the bark and into the wood to a depth of 1 cm. and the piece then 
removed with a small knife. The injured area was then filled 
with grafting wax. 
The material collected from trees A and B was fixed in a 
solution consisting of 33 parts glycerine, 35 parts alcohol, 30 parts 
distilled water, and 2 parts glacial acetic acid. The material 
kept in this solution was in excellent condition for sectioning, 
though, of course, no good fixing of the protoplasmic structure 
was obtained. That collected from trees C and D was fixed in 
Gilson’s solution and kept, by mistake, in 95 per cent alcohol. 
When attempts were made to section it, several months later, 
considerable difficulty was experienced, because of brittleness. 
Attempts to soften the material, by allowing it to remain in equal 
parts of glycerine and alcohol, and also in glycerine alone, proved 
futile. The greater part of the material was sectioned without 
imbedding, but some of it was necessarily imbedded in celloidin. 
The sections were cut from 20 to 40 yw in thickness and stained with 
safranin and Delafield’s haematoxylin of the formula so commonly 
used for wood staining. The methods employed during the 
season of 1911 are described subsequently. 
INVESTIGATIONS OF 1909_ 
The first cuttings were made on April 19 and at this time 
the buds located on the 4-, 5-, and 6-year old wood had opened, 
