Noteworthy anatomical and physiological researches. 
On the twisting of the grain of pine,! 
In 1854, A. Braun? published the results of extensive ob- 
servations on the twisting of the grain in a large number of 
species of wood-producing plants, and offered an explanation 
for the phenomenon. The paper now under consideration 
contains the results of investigations on a limited number of 
allied species of conifers. Dr. Hartig agrees in part with 
Braun in his explanation, but does not agree with him as to 
the final cause of the twisting of the grain. The former as- 
signs as the cause the peculiar manner in which the increase 
inthe number of elements of the cambium occurs. As the 
Woody axis of the tree increases in diameter the number of 
lements in the cambium cylinder at any height must in- 
‘ease correspondingly. This increase in the number of ele- 
ments is secured not by division in a radial plane, but by 
transverse divisions. Usually these divisions do not occur at 
“xactly a right angle to the long axis of the cell. As the two 
daughter cells produced by such a division, grow in length, 
the Upper end of the lower one pushes its way upward and 
the lower end of the upper one grows downward, each insin- 
lating itself between its mate and the neighboring element, 
Parating to a slight degree the original elements of the cam- 
om sheath, thus increasing its diameter. : 
th hese transverse walls are inclined both to the right and to 
€ left from a radial plane. Between the relative members 
of these two kinds of wall and the twisting of the grain there 
= Close relation. Generally if the members are about equal 
th stain is straight. If a large majority of them incline to 
“Tight the grain winds in that direction; if to the left, the 
t ; - 4 
Zaina gest: Ueber den Drehwuchs der Kiefer. Forstlich-naturwiss. 
a B : 
313-326. Ag. 1895. at . 
Seng Me Ueber a. schists Verlauf der -Holzfaser -_ oa — 
1854 ehung der Baiime. Sitzber. der kgl. pr. Akad. ; 
[159] 
