Manchester Mevioirs, Fo/. x/v. (igoi), No. t. 17 



than in LepidopJiloios, the large elements are often con- 

 tiguous, an appearance suggestive of the arrangement of 

 the sieve tubes in living Lycopods. Within the outer and 

 distinct band of phloem elements, and separated by a dark 

 band of tissue, are seen some smaller groups of soft bast 

 cells, similar in structure to those nearer the outside, but 

 less regular in arrangement. Besides these there are also 

 two groups of smaller and harder elements which appear 

 to be the commencement of leaf traces, one already partly 

 imbedded in the phloem region. In other parts of the 

 section can be seen the early stages of disorganisation of 

 the phloem elements by a breaking away of the cell walls 

 separating adjoining sieve tubes. This process, as has 

 been stated above, results in this species of Lepidodcndroii 

 in the complete disappearance of the phloem elements. 



The phloem of the leaf traces is not sufficiently 

 preserved in this specimen to enable me to ascertain the 

 presence of what Hovelacque^ described as laticiferous 

 cells which occur more particularly in the phloem of the 

 leaf trace bundles. They appear according to this author 

 to be very variable in their number, and sometimes, as he 

 says in his note on page 51. "II faut meme etre prevenu 

 qu'il peut y en avoir pour les decouvrir." J have mentioned 

 in a previous part of the paper what I consider to be the 

 possible nature of such cells as seem to occur in the stem 

 and leaf traces of various Lepidodendra. 



Summary. 



Having now examined the cells making up the phloem 

 region of LepidopJiloios and Lepidodendron respectively in 

 two of the best preserved specimens, I think we cannot 

 but conclude that the arrangement of its cells, as seen at 



^ Hovelacque, loc cit. 



