xviii Proceedings. {^February 2^th, igoS. 



spirally thickened portions of the vessel and by the enlarge- 

 ment of the tylose-like processes so formed, break up the 

 vessels, replacing them by a strand of large-celled parenchyma. 

 In Nephrolepis the passage of undivided xylem sheath cells 

 through a series of two or three vessels can be seen. Other 

 plants examined in which cavity parenchyma is present, were 

 StrutJiiopteris, C/ieila>ithes, Gyinnograinme, Pteris, Marattia, 

 Angiopferis, Osmunda, G/eichenia, Aneimia, Hehninthostachys, 

 Alsophila, Dicksonia, Heiiiitelia, and Cibo/iuin. In the last 

 named occurred a condition not found in any other plant. 

 Throughout the length of the strands of cavity parenchyma, 

 some of the cells were lignified in a reticulate manner as tracheids 

 resembling the " Speichertracheiden " described by Haberlandt. 

 These lignified cells occurred sometimes singly sometimes in 

 groups, but the groups were not connected with each other, and 

 were thus probably not for conducting, hut for storage purposes. 

 The other cells of the strand were of the usual soft-celled type. 

 The occurrence of such tylose-like formations in recent ferns 

 may be compared with the tyloses filling up the metaxylem 

 tracheids in some of the fossil ferns, as in Rhachiopteris insignis, 

 their presence in this case being due to the activity of all the 

 cells of the xylem sheath and not simply of those bordering on 

 the protoxylem. 



General Meeting, March loth, 1908. 



Dr. VV. E. Hoyle, F.R.S.E., Vice-President, in the Chair. 



Mr. W. H. Fowler, M.Inst.C.E., was elected an 

 ordinary member of the Society. 



