Histological Studies in the Artemisia Formation 21 
rupture (schizogenous in part) and disorganization of more or 
less permanent tissues. The beginning is marked by a single cell 
filled with a dense, yellowish-brown, mucilaginous protoplasm, 
figure 35. This cell stands out very plainly among the clear sur- 
rounding cells of the storage region, and this, the primordial cell, 
marks the position of the future canal. The color and mucilag- 
inous or. resinous appearance spreads from the first cell to those 
adjacent, and subsequently the walls of the primordial cell are 
dissolved and the several secretory cells thus opened contribute 
their contents to the young canal, figure 36. This disintegration 
and solution proceeds for some time until finally the cavity of the 
canal appears, figure 37. In the mature state the cavity is sur- 
rounded by the epithelial-like layer of secretory cells. Finally, 
an open longitudinal canal is formed with the structure shown in 
figure 38. 
The function of these canals or of the secretion can not be ex- 
plained at present. The chemical composition of the resinous 
secretion was not determined. _ 
Juncus balticus, Plate VII and plate VIII. 
This species furnishes the most striking differences in structure 
between the moist and the dry form found during this study. The 
material from which both the figures were made was collected at 
Fort Garland where the species was found widely distributed in 
the wet meadow north of the village and also in the adjacent 
Artemisia formation. In the wet meadow the species formed 
close, compact groups interspersed with various species of Carex, 
but in the Artemisia formation it occurred as rather widely scat- 
tered individuals. It did not occur in close groups in this habitat. 
Figure 41, plate VII, was made from the moist form. The soil — 
in the meadow was covered with an inch of water, therefore it 
may be considered saturated. Figure 42, plate VIII, was made 
from the dry form from the Artemisia, where the holard was 10 
per cent. Both figures were made at the same height from the 
ground. 
These two stems show such a great difference in structure 
that, although from all that could be made out, they are from the © 
same species, there is the possibility that we may have here two 
431 
