362 Jeffrey and Cole.— Experimental Investigations 
in this case likewise present on the right, while the illustration as a whole 
shows only parts of tracheides. The pits are appreciably smaller than are 
those of D. color ata in the preceding figure. Fig. 6, PI. VII, shows a view 
of the root wood of D. colorata. The pits are now in two rows, in contrast 
to the single series characteristically present in the woody structures of the 
stem. The increase in number of pits appears to be a usual feature of 
organization of the wood of the root both in Dicotyledons and Conifers. 
The pores of the tracheides in the figure alternate in the araucarian manner, 
but are not deformed by approximation and mutual pressure as in the 
subtribe of Conifers indicated. 
The most interesting conditions which have been observed in the 
present connexion have been found in the case of the root wood, when 
injured. Two large adult roots and the roots of a number of seedlings of 
D. colorata showed the presence of healed wounds. For comparison with 
these was available a large amount of normal material. It should be stated 
that the results recorded here depend on the examination of a considerable 
number of preparations, and have to that extent a general validity. Fig. 7, 
PI. VII, reproduces part of a longitudinal radial section of a wounded root 
in the vicinity of the injury. To the left in the figure appear tracheides 
filled with a dark gummy material, which is one of the consequences of 
injury. A curious phenomenon is seen in some of the tracheides, most 
strikingly visible in the fourth element from the right. Here, instead of the 
rows of separate rounded pits, which are characteristic of the normal 
structure of the root, we find elongated scalariform pits, such as are often 
present in vessels of the Magnoliaceae and other dicotyledonous families. 
To the left of the element under discussion is one in which the scalariform 
pitting is less pronounced, and in the next tracheide to the right of the first 
described it can scarcely be observed. Fig. 8, PI. VII, shows another field 
of view from a different root (likewise wounded). Crowded pitting occurs 
in the tracheides on the right and left of the figure. To the left of the 
centre in the figure lies a tracheide in which scalariform pitting is a marked 
feature. A careful inspection of the pits in the upper and lower regions of 
this element makes it clear that the scalariform pits are the result of the 
fusion of the rounded pores, which are a feature of the organization of 
the normal tracheides of the wood of the root. Two or three rows of 
parenchyma can be made out in the illustration. Fig. 9, PI. VII, furnishes 
us with still another view of injured wood in the root of D. colorata . Here 
may be observed a great variety of conditions in regard to the fusion of 
pits in the tracheides. In an element to the left of the centre the condition 
of fusion is very marked, and the scalariform pores resulting from it are as 
a consequence much elongated. Farther to the right and left all stages of 
fusion may be made out in the case of the small round pits, which are 
a normal type of pore in the elements of the root, An examination of 
