94 THE UNIVERSITY SCIENCE BULLETIN. 



cerning the development of the leaf -trace bundles in the Cheno- 

 podiese: "The leaf -trace bundles sometimes possess considerable 

 growth in thickness, and thus delay the appearance of the anoma- 

 lous growth {Camphorosma and Echinopsilon, as also Blitum vir- 

 gatum, Chenopodium murale and C. hybridum, according to De 

 Bary, Kochia prostrata according to Georghieff.) " 



As seen in some cross sections of region IV, and regions farther 

 down the stem, the primary vascular bundles are very irregularly 

 arranged, are more numerous than in regions higher up, and have 

 the appearance of being imbedded in the pith. (See figs. 5, j, 

 and 6, j.) This appearance is due to the fact that the cells in the 

 areas of primary pericycle e" and g of fig. 26 and the cells of the 

 primary medulary rays (fig. 44, g) in these regions of stem resem- 

 ble pith cells in shape, and appearance of cell walls, which have 

 remained cellulose or are very slightly lignified. 



A few cells of the area of pericycle, e", which have cellulose 

 walls, are shown in longitudinal section of region IV in fig. 46. 

 In regions of stem from region IV on down, parts of the anoma- 

 lous xylem, which is first formed exterior to the primary vascu- 

 lar bundles by anomalous growth, resemble pith. This is shown 

 for region V in fig. 26. A discussion of the origin and nature 

 of the anomalous tissue appears later in this article. 



The following statement quoted from Solereder ('08) throws 

 light upon the pith-like appearance of the primary pericycle and 

 primary medullary rays in most sections of region IV and all 

 sections of regions below: " In the Nyctaginege, Amarantaceae and 

 Chenopodiacese the ground tissue situated between the primary 

 vascular bundles and the tissue formed at the commencement of 

 the activity of the secondary meristem is occasionally diff"erenti- 

 ated like a pith, and in such cases the primary vascular bundles 

 appear as apparent medullary bundles." Solereder also states 

 that the vascular bundles, which he terms medullary bundles, 

 appear in certain members of the Chenopodie^, and adds that 

 their development in this order shows that these bundles are 

 rarely true medullary bundles, but are the normal leaf-trace 

 bundles. According to Georghieff (fide Solereder), true medul- 

 lary bundles occur in Acroglochin persicarioides Moq. Bll^ 



Evidently the primary vascular bundles of Cycloloma atriplici- 

 folium have the same appearance in region IV and regions on 

 down the stem as have the bundles which Solereder terms apparent 

 medullary vascular bundles. 



