Barber . — Cupressinoxy Ion vec tense. 347 
In root (2) well-defined rings are absent near the pith. 
Besides this, where the rings are visible, it is found that 
the largest cells are in the middle of the ring, those at 
the commencement being considerably smaller. I have, 
accordingly, measured the ten tracheides at regular intervals 
from the centre or in the middle of each ring. 
Root (2) | 10-5 [ 14 | 20 | 25 | 26 | 32 ] 29 | 26 | 33 | 26 | 26 | 26 ] 28//. 
The branches show the increase in radial diameter which 
was to be expected. The roots show first an increase in 
width, followed by a decrease in succeeding rings. Without 
laying much stress upon this latter peculiarity, because of 
the fewness of observations, it may be pointed out that the 
arrangement is in accordance with the results obtained by 
Sanio. He showed that while in branches the increase in size 
of the tracheides is maintained until a constant is reached, in 
roots these elements increase in radial diameter during the 
first few years, then decrease, later on again increasing until 
a constant is reached \ 
It is important to note that, according to Mohl and other 
observers, the elements of roots are larger than those of 
stems and branches. This does not hold good in the present 
case, a fact which throws some doubt upon the division of 
our specimens into roots and branches 2 . 
An examination of the summer-tracheides, on the other 
hand, tends to support this division. The summer-elements 
of roots are stated by Mohl to be fewer in number and less 
flattened than those of branches and stems 3 , and this appears 
to be the case in our section. I have collected for comparison 
the most flattened elements of each ring, and have in each case 
tried to get as many in a radial group as possible (cf. Figs. 2 
and 3). 
1 Sanio, 1 . c. 
2 Nordlinger, Forstbotanik, mentions cases where there is not much difference 
between the size of cells in stems and roots (Aspen, &c.). 
3 Mohl, 1 . c. 
