4 Weiss, Phloem of LepidopJilcios and Lepidodendron. 



phloem region which stretches from here to the some- 

 what dark band forming the boundary between the central 

 vascular cylinder and the cortical region. The phloem 

 which, as stated above, is usually very defective in Lcpido- 

 phloioSy sometimes indeed entirely disorganised, is here, 

 as can be readily seen from Fig. i, completely preserved, 

 though its tissues are somewhat confused in the thicker 

 portions of the section. It will be noticed at once that 

 it is not characterised by those large spaces figured by 

 Williamson' and which Seward regards as secretory 

 sacs. The largest cells in the phloem are not as large as 

 the cells of the cortex, while the so-called secretory sacs of 

 the less well-preserved specimens are far larger than the 

 cortical cells, as large indeed as the larger vessels of the 

 primary wood. We can therefore only conclude that when 

 such large spaces occur they are due to the decay, 

 previous to mineralisation, of whole groups of cells. The 

 only other alternative, namely, that the tissue was not yet 

 fully mature, seems precluded by the presence of so large 

 an amount of secondary tissue. 



On closer examination of the phloem it will be 

 observed, as is perhaps better seen in a more enlarged 

 view {Fig. 2) of the thinnest portion of Fig. i, that the 

 largest cells of this tissue are generally surrounded by a 

 somewhat regular and star- shaped group of cells. Two 

 such groups are well seen towards the right-hand side 

 of the phloem in Fig. i and on a larger scale in Fig. 2. 

 Separating such groups are cells of various sizes some- 

 what irregularly placed. 



Another enlarged view of the phloem from a very 



thin portion not included in Fig. i is represented in 



Fig. 3. Though the tissues in this portion of the phloem 



region seem somewhat confused, one or two groups 



1 Williamson, W. C, ioc. cit. Plate 49, Fig. 11. 



