432 BOTANICAL GAZETTE [DECEMBER 
The roots : 
In considering the internal structure of roots that are simply nutri- 
tive and of no long duration (perhaps only one season), we must not 
expect to find great modifications. In regard to the Gramineae we 
have learned from Kurncr’s® interesting paper that certain 
modifications may be observed in the structure of the cortex, whether 
persisting or collapsing, whether homogeneous or differentiated as 
distinct zones of parenchymatic or stereomatic strata; also in the 
thickening of the endodermis, and in the structure of the pericambium, 
whether it is continuous or interrupted by the proto-hadrome. The 
presence or absence of an exodermis also seems to be worth mention, 
and the structure of the parenchyma in the stele, which sometimes 
represents a central pith. Much attention has been given to the 
position of the proto-hadrome vessels, whether they are inside the 
pericambium or border directly on the endodermis. In some instances 
all these vessels have been observed to occupy the same position in 
reference to the pericambium; but in other instances a variation has 
been noticed, where only some of the proto-hadrome vessels had 
broken through the pericambium. In studying root structures: of 
different plants, especially of monocotyledons, one gets the impression 
that the continuity or interruption of the pericambium is of some 1° 
portance and constitutes a good anatomical character. In very 
many roots I have found a constantly continuous pericambium oF @ 
constantly interrupted one; but on the other hand, as shown ™ 
Eriocaulon and Carex,® there are also cases where this structure is not 
constant, but varies from the base to the apex of the same root. This 
peculiarity I noticed by making consecutive sections of a number of 
roots, and it appears therefore as if the structure of the pericambium, 
‘so far as concerns its continuity or interruption, is not a character 1° 
be depended upon. In Deschampsia caespitosa and Festuca diages 
from Europe, KiincE (I. c., p. 56) observed the proto-hadrome 
vessels bordering on the endodermis; while in these same epee 
from Colorado all the vessels were found to be inside the pericam 
* i i oe 
8 KLINGE, Vergleichend histiologische Untersuchung der meg es Imp- 
Cyperaceen-Wurzeln insbesondere der Wurzel-Leitbiindel. Mém. rs 
St Petersbourg VII. 26: No. 12. 1879. . 
° Bor. Gazetre 31:17. 1901; and Am. Journ. Sci. 102278. 1900- 
