14 Weiss, Phloem of LepidopJiloios and Lepidodendron. 



in the Binney preparations. This is due partly to the 

 bundles being cut somewhat obliquely, and partly to the 

 greater thickness of the section at those points where the 

 leaf traces are cut as nearly transversely as possible, i.e., 

 in the region of the inner cortex. In the mid-cortex 

 the leaf trace bundles run almost horizontally in typical 

 specimens of this species, but in the inner cortex they are 

 sufficiently nearl}' vertical to be approximately transversely 

 cut in a transverse section. Two such sections across the 

 leaf trace bundles are shown in Figs. 6 and 7, and they 

 both show the same features as regards the structure of 

 the phloem, and this is shown in the case of other bundles 

 not figured. It will be seen that the phloem consists of 

 some three rows of large-spaced elements somewhat 

 irregular in outline though with some regularity in their 

 arrangement. These large cells are apparently not 

 separated by smaller elements but adjoin each other, and 

 in this respect the phloem resembles the arrangement of 

 the tissue in the stems of many of the living Lycopods, 

 where single rows of large sieve tubes adjoining each other, 

 and with only a row of small elements at the top and 

 bottom, run in between the xylem groups. 



Whether this appearance was the actual condition of 

 the living tissue is difficult to say in view of the difference 

 between our figures and those of Binney and of Seward, and 

 though the appearance does not seem to warrant it, a disor- 

 ganisation of the tissue may alread)' have set in in the leaf 

 trace bundles. If, however, that is not the case, we have an 

 interesting feature in the absence of the numerous small 

 cells which separated the larger elements of the stem. If the 

 smaller elements have the same function ■as the companion 

 cells or of the phloem parenchyma of Angiosperms their 

 absence or reduction in the leaf trace bundles should not 

 surprise us ; for they have been looked upon as collecting 



