1886.] BOTANICAL GAZETTE. 53 
is very sharply defined ; whereas the outline of the base is much 
fainter, and the whole pit seen from above appears as a very 
definite pit whose transverse diameter is the greater, surrounded 
by a much less distinct, but usually quite evident circle marking 
the original outline of the pit (figures 8 to 10). In _pro- 
portion as the pits are more or less elongated and crowded, the 
tracheid approaches more those of the ferns or gymnosperms. 
could not certainly determine whether or not the bottom of the 
pit was finally absorbed. There isa general correspondence in 
the place of formation of pits on the adjacent walls of neighbor- 
ing tracheids, but not so marked as is often the case. Some- 
times the thickening of the wall is uniform between the pits, so 
that they retain the form of unbordered pits. 
The bundles differ in form in the main and lateral roots. 
In the former the mature bundle has a nearly triangular sec- 
tion, the xylem consisting of three radially placed oval masses 
of tracheary tissue, with three masses of rather thick-walled, 
imperfectly deveioped sieve tissue, constituting the phloems lying 
etween. The limits of the oem masses are not very clear, 
merging more or less into the thin-walled parenchyma, constitu- 
ting the rest of’ the fibro-vascular cylinder. In the lateral roots 
the bundle is oval in outline and the xylem and phloem in two 
masses instead of three (figure 6). In neither case do the sep- 
arate masses coalesce. In one case a very strong main root showed 
four instead of three xylem and phloem masses. 
"he phloem consists of elongated cells of varying diameter, 
some of the larger ones with the transverse walls only slightly 
oblique, probably being undeveloped sieve-tubes. The rest 0 the 
cells are narrower, with much more oblique walls, so that their 
ends are often decidedly pointed ; otherwise they differ but little 
rom the surrounding parenchyma. 
EXPLanation or Piare IV .—Fig. 1. Longitudinal section through the 
apex of a main root of Botrychium ternatum. < 150. a, apical cell. pr, pro- 
cambium cylinder. ¢, root-cap. : 
ig. 2. Transverse section through the region of the apical cell. 
The first six lateral segments are num . pepe. 
Fig. 3. Young segment of root cap, showing the first division walls, 1 
and 11. >< 245, 
150. 
6; 1gs. 4-6. Transverse sections through the young bundle of a lateral root. 
18 practically complete. ph, phloem. ry, xylem. 245. i 
Fig ei selattadiaa! Foe da of the bundle of a main root, of about the 
age of Fig. 6, showi : ids, tr. ‘ 
v% 8 6, showing the primary tracheids, #7 adie ob with node 
