348 Barber . — Cupressinoxylon vectense . 
Measurements of summer -tracheides. 
No. of groups 
measured. 
Branch (i) 20 
Branch (2) 13 
Root (1) 31 
Root (2) 25 
Average number of 
tracheides in a group. 
Average radial diameter 
of tracheides. 
4*3 
5-4 
3 
3 
hi M 
9*8 
12 /X 
12*2 fJL 
The walls of the tracheides are frequently seen to be 
striated in longitudinal sections. This is especially the case 
where, from the appearance of the bordered pits and the 
presence of fungus hyphae, it is evident that decomposition 
had commenced before petrifaction. The striation in these 
cases is probably due to this cause. In tangential sections, 
however, the summer-wood is seen to be striated even in well- 
preserved parts where the spring-wood is not — a phenomenon 
not due to decay, but often met with in the wood of recent 
Conifers. 
The thickness of the walls of the tracheides, a character 
which was once considered to be absolute, varies a good deal 
with the state of preservation of the part. An average of 
80 measurements gives 7*3^, ranging from 4ju to 14/1. 
Bordered Pits. 
The bordered pits have received the utmost attention from 
students of wood structure. By means of these, Coniferous 
wood is easily separated from that of Angiosperms, and of 
the former the Araucarian type is cut off from the rest. 
There are also subordinate differences in the sizes of the 
bordered pits and the numbers of rows per cell in stems, 
branches and roots. Since in Coniferae they occur ex- 
clusively upon the radial walls, the study of radial sections 
has acquired great importance in diagnosis. 
The bordered pits in our sections are arranged in one row — 
probably in great part due to the youth of the specimens. 
A comparison of the radial diameter of the tracheides and 
