STRUCTURE. 53 



can only be traced so far as to show that all of the four stolon-bundles 

 are sooner or later joined by leaf-traces, and therefore that all of the 

 bundles of the stem are common. 



Concerning the origin and distribution of the bundles in the stolon of 

 N. flava, we can only say that at the distal end of the stolon the vascular 

 strands branch and anastomose, in fusing with leaf and root traces, to 

 form the vascular cylinder or plexus of the new caudex. The strands of 

 the stolon originate from the four sides of a ramular gap in the vascular 

 system of the parent plant similar to a leaf-gap, and the stolons occur in 

 the place of leaves in the leaf-spirals of the surface of the stem. The 

 above evidently refers to a stolon with four vascular strands, which seems 

 to be the normal number. I have examined one specimen with five 

 strands, one central and four peripheral. In this the central strand fused 

 with the lowest peripheral one before entering the parent stem, so that 

 both passed in as a single strand over the brink of the ramular gap 

 exactly like a central leaf-trace. 



It would seem from these accounts that the bundles of the stolon are 

 scarcely to be called steles, and that the behavior of the leaf-traces is 

 more in line with dicotyledonous than with monocotyledonous structures. 

 Prof. Nageli remarked in 1857 (Caspary, 1857, b} that "of the five 

 vascular bundles which enter each leaf in N. alba, the two lateral pairs 

 in the interior of the stem go to the sides of the stem, but the middle 

 one sends a branch inward to form a central strand, and only in this 

 latter point does N. alba differ in structure from the characteristics of 

 a dicotyledonous stem." 1 



The relations of the bundles of the flower stalk in joining the stem 

 have been most accurately worked out in N. flava. Seventeen longitudi- 

 nal bundles were found in the peduncle, viz, a central bundle ; four large 

 ones 90 degrees apart around the periphery, of which one is anterior, 

 one posterior, one right and one left ; alternating with these are four 

 smaller bundles, and eight tiny ones alternate with the last two sets. The 

 last eight were not traced into the stem, but they doubtless unite with 

 their larger neighbors at the base of the peduncle. Great variation exists 

 in the details of the fusion and anastomosis of the remaining bundles, 

 Fig. 22, (/;). However, it seems constant for the four oblique bundles to 



" dass von den 5 Gefassbiindeln, die bei N. alba in jedes Blatt eintreten, die beiden 



seitlichen Paare im Innern des Stammes nach dessen Rande zugingen, das mittlere jedoch einen 

 Zweig- nach Innen entsende, urn einen centralen Strung zu bilden, und nur in diesem letzteren 

 Punkte weiche der Bau von N. alba von dem Charakter des Dicotyledonenstammes ab." p. 791-2. 



