1906] CHRYSLER—NODES OF GRASSES 5 
qu’au noeud suivant.” See further his remarks on the monocoty- 
ledons. 
Phalaris arundinacea, like Avena, has the bundles of its internode 
crowded into an annular area surrounding the fistular pith. As 
these reach the node they anastomose extensively, and at the same 
time assume the amphivasal condition, which is shown with especial 
clearness in the variety variegata, figs. 3 and 4, the latter more highly 
magnified in order to show the tendency for bundles to form nests 
of three or more, enclosed by an armor of sclerified fibres. These 
amphivasal bundles, though abundant in the nodes, are absent from 
the internodes. 
Arundo Donax may be mentioned as typical of species having 
several circles of bundles surrounding a central cavity. As the leaf- 
trace bundles enter the stem they swell out, though not to so great 
an extent as in Avena. The xylem completely encloses the phloem, 
and the usual suberized sheath of cells with reticulately thickened 
walls becomes visible. Farther down in the node the leaf-trace 
bundle is joined on each flank by one or more cauline bundles. 
The bundles of the latter class are provided with a sheath of heavily 
thickened cells, and some of them appear to pass through the ncde 
without anastomosing with other bundles, though this condition is 
rare in the members of the family which have fewer bundles. In 
accordance with the greater thickness of the solid part of the stem, 
the leaf-trace bundles penetrate more deeply into the central cylinder 
than in such genera as Avena, making their general course conform 
more nearly to the palm type of von Mont. The number of circles 
of bundles in an internode appears to be dependent on the size of 
stem characteristic of the species, and to have little value in estab- 
lishing relationships. 
Grasses with a solid stem conform even more nearly to VON Mount’s 
type, for the largest leaf-trace bundles penetrate nearly to the center 
of the stem, before curving outward and downward toward the 
periphery of the central cylinder. STRASBURGER (4) has given an 
excellent account of the course of the bundles in Zea Mays. He 
distinguishes leaf-trace bundles of five different ranks, and finds 
that the largest of these penetrate most deeply into the stem, while 
the smallest merely reach the periphery of the central cylinder. 
