180 Transactions. 



peripherally as to form an interrupted cylinder around the stele. They 

 are also only feebly lignified. This nature of the xylem and protoxyleni 

 in L. Drummondii gives a very characteristic appearance to the stele 

 as a whole, and one which is in marked contrast to its appearance 

 in the other divisions of the genus. Moreover, it is found, as will be 

 shown below, not only in the Inundata, but also in the Cernua section. 

 In the ultimate branches, and in the fertile branch of L. Drummondii, 

 the configuration of the vascular tissues is more definite, as would be 

 expected where the vascular elements are much fewer in number, and 

 the xylem might also be described as radial. The protoxylem groups, 

 however, are just as much extended peripherally as in the larger parts 

 of the plant, and the individual elements of the metaxylem are just as 

 feebly lignified, so that it is apparent that right throughout the plant 

 a consistent type of stelar anatomy and of vascular histology is to 

 be found. Jones (21) describes the stelar anatomy of the strobilus of 

 L. inundatum as radial, and notes that in the branches a striking tetrarch 

 structure is obtained. In his figure of this he shows both xylem and 

 protoxylem as being very broad at the periphery. This is very similar 

 to what I have just described for L. Drummondii. The cortex in 

 L. Drummondii shows an inner narrow more or less sclerenchymatous 

 zone which is more strongly developed in the erect fertile branches, 

 whilst the main cortical tissue consists of large spongy parenchyma with 

 abundant air-spaces, grading ofl' externally into a very ill-defined epidermis. 

 I have been unable to find a mucilage-cavity in the leaf such as has been 

 described in L. inundatum. 



The Young Plant. 



I was not successful in my search for the prothallus of this species, but 

 alono- with the adult plants I discovered a large number of plantlets of all 

 sizes which seemed to have originated vegetatively. All the specimens 

 which I have preserved are of small size and are unbranched. They very 

 earlv adopt the plagiotropic habit, and at once begin to develop adventi- 

 tious roots. Such specimens as are complete show that at the base the 

 plantlet is prolonged directly into its first root, and that the vascular strand 

 is continuous throughout this root and the shoot. In one or two instances 

 I could clearly trace a broken prominence where the shoot passes uito the 

 root, at which spot presumably the plantlet had been attached to the parent 

 body. One specimen consisted of a small old piece of rhizome with its roots, 

 and attached to the rhizome was one of these plantlets showing both shoot 

 and root. From this specimen, and from indications on many of the others, 

 I therefore judge that the plantlets are propagative shoots which arise on 

 the older rhizomes at the season of the year when the latter are beginning 

 to die oft". They give evidence of no structure which can be likened to a 

 protocorni. This is noteworthy, for we should rather expect to find that 

 the embryogeny of this species would show a protocorm stage, and that 

 even vegetatively produced plantlets would also possess this structure, as 

 do those of L. ramnlosnm, which I have described elsewhere (17). 



SECTION CERNUA. 



Belonging to the section Cernva are the New Zealand species L. laterale, 

 L. cernuum, and probably also L. ramulosum. 



