334 BOTANICAL GAZETTE [APRIL 
wood of the following year. Between these and the summer wood 
of the same year neither kind of element is to be found. 
Another species in which ray tracheids were found is A. homo- 
lepis. Fig. 8 shows a ray in the region of the annual ring. On the 
upper margin are ray tracheids in line with a parenchyma cell. 
Fig. 12 is a more magnified view of these elements, and shows the 
bordered character of the pits more distinctly, especially of the 
two on the end wall. The material of A. homolepis is particularly 
interesting from the fact that it exhibited no trace of wounding 
either in radial or transverse sections. As the segment was of 
considerable length and contained ray tracheids throughout, the 
presence of the latter could scarcely have been the result of a dis- 
tant wound, especially as there was no trace of traumatic canals. 
Their presence, therefore, must be considered as normal, or at least 
sporadic. 
The only other species in which these structures were observed 
is A. Veitchii. Fig. 11 demonstrates their presence in this form, 
the bordered pit on the end wall being most distinct. The material 
was similar to that of A. homolepis, a branch which showed no 
trace of wounding. As in the other species, their typical position 
was in the spring wood following one or two parenchymatous cells 
in the summer wood of the previous year (see fig. 11). 
Many other species were examined, including A. Jasiocarpa, 
Fraseri, Nordmanni, cephalonica, grandis, balsamea, and firma, but 
none were found to have ray tracheids. A very diligent search 
was made in the case of A. balsamea, in which PENHALLOW reports 
having observed them sporadically. Normal and wounded roots, 
stems, branches, and seedlings, as well as witches’ brooms, all failed 
to show a single indisputable ray tracheid. However, material 
collected during the active growing season and examined in the 
cambial region showed a slight border on the pits of some of the 
cells, which from their position were evidently doomed to degen- 
eration in a manner to be described below. 
In all those species in which ray tracheids were found, their 
position and association with neighboring cells were very suggest- 
ive. As has been described, they usually occurred in the spring 
wood, and were conterminous with one to several parenchyma 
