122 STEM STRUCTURE OF Hemitdiu CapL'HSis. 



above and below. This elongate spindle form explains the ap- 

 pearance, in transverse section, of apparently larger and smaller 

 steles, as it is obvious that the smaller ones are the ends of strands, 

 while the larger ones are sections at or near the centre, where they 

 are thicker. 



This structure suggests that the inner system is possibly the 

 remains of an ancestral reticulate system, separate from that 

 of the large bundle tube and connected to it only by the two leaf 

 traces entering each foliar gap from within. From the above 

 description it will be seen that the vascular structure is less com-, 

 plicated than that of other Cyatheaceae, being marked by the 

 absence of such free anastomoses as occurs in other genera. 



My thanks are due to Mr. "U\ T. Saxton, who suggested this 

 investigation, which was carried out in the Botanical Laboratory 

 of the South African College, Cape Town. 



LITERATURE QUOTED. 



1. De Bary : " Comparative Anatomy of the Phanerogams and 



Ferns." 



2. Mettenius :* " Ueber den Bau von Angiopteris." Abhandl. d. K. 



Sachs. Gesellsch. d. Wissensch. IX. 



EXPLAXATIOX OF TEXT FIGURES. 

 Fig. I. Transverse section of stem with old leaf bases and other decayed 



matter removed: A, fibrous layer; B, ground tissue; C, 



sclerenchymatous sheath of bundle ; D, phloem ; E, xylem ; 



F, leaf trace ; G, cauline steles. 

 Fig. 2. Sketch of portion of bundle tube showing pairs of leaf traces passing 



into the foliar gaps : view from the inside, i natural size. C, D, 



E, F, as in Fig. i ; LB, leafbase. 

 Fig. 3. Sketch of same but from the outside, showing rings of bundles arising 



from the foliar gaps. LB, leafbase ; SP, sclerenchymatous 



plate ; F, leaftrace from pith ; G. leaftraces from margin of 



foliar gap. 

 Fig. 4. Transverse section of petiole. F. leaf traces from the pith ; G, 



inner two from margin of gap ; A, epidermis ; B, ground tissue. 



TRANSMUTATION OF ELEMENTS OF THE CARBON 

 GROUP. — Ramsay and Usher announce (Berichte, iqoq, \'oL 

 42, pp. 2930-2931). that they have submitted solutions of different 

 salts of the Carbon group of elements to the action of radium 

 emanation for four weeks. The emanation had in each case, 

 been carefully freed from Carbon dioxide, but the latter was, 

 in every instance, subsequently found in the resulting gas. some- 

 times accompanied by carbon monoxide. The elements thus 

 experimented upon were Silicon. Titanium, Zirconium. Thorium, 

 and Lead, and the conclusion is expressed that each of these 

 elements, without exception, gives rise to carbon compounds under 

 the action of radium emanation. Lead appeared to be the most 

 stable, and to exhibit least tendency to change into carbon. 



* The latter paper could not be procured here, so that it was impossible 

 to ascertain how much of the work had already been done. However, the 

 few remarks on the subject, which were got froni De Bary's work, seemed 

 to point to the fact that the investigation (if any real study of the stem has 

 ever been, undertaken before) was either very superficial, or carried out witii 

 insufficient material. 



