492 SUMMARY OF CURRENT RESEARCHES RELATING TO 



with that of the branches, showing the branches to be attached in 

 quite a normal way. These branches themselves show the ordinary 

 bushy, spreading mass of small branchlets usual in known examples of 

 Bothrodendron. It is equally clear that the other specimen is a similar 

 though larger branch which has fallen away, its clear-cut, trumpet- 

 shaped ending suggesting that it has broken away along a definite 

 abscission layer. Though previously described examples of Bothrodendron 

 in the ulodendroid condition have been attributed to B. punctatum, the 

 fact that the two new specimens are B. minutifolium is not an un- 

 surmountable difficulty, since these two species, if not identical, are at 

 any rate very closely allied, and it is therefore quite probable that both 

 had the same method of shedding. 



Vascular Development in Osmundaceas and Gleicheniaceas.* — M. 

 Jossa describes the development of the conducting tissue in the 

 rhizomes of the Osmundaceas and Gleicheniaceas. Her conclusions are 

 that, putting aside homologies and the interpretation of organs already 

 developed, and studying instead the development from the growing- 

 point, one finds that: — 1. The so-called "mesarch" bundles of the 

 Osmundaceas begin always in the form of divergents. They are closed 

 divergents, the protoxylem being able besides to disappear secondarily 

 (in Gleicheniaceas) or to be absent from a part of the bundle, par- 

 ticularly in the stipes, as a consequence of diminished growth. •!. The 

 Osmundaceas possess a true central and single cylinder (stele, not dictyo- 

 stele), in the interior of which there is an early development of endarch 

 ligneous vessels, flanked later by centripetal ligneous wings. 3. The 

 leaf-trace, detaching itself from the central cylinder towards the leaf, 

 may become divided, but remains in perfect continuity with the cauline 

 trace, without modification of its orientation or direction. 4. The com- 

 plex portions, which may form themselves into the central cylinder of 

 the Osmundaceas, are the homologue of the portions of the ligneous 

 ring of the central cylinder, equally unique of the Gleicheniaceas. 

 5. Finally, the protostele of our species (the analogue, but not the 

 homologue of the protosteles of the rhizomes in certain higher plants), 

 where the xylem finally occupies the whole centre, has its origin in a 

 ring which results from the concrescence of isolated cauline bundles, or 

 perhaps of leaf -traces with centrifugal metaxylem. 



Anatomy of Cone of Equisetum.f — Isabel M. P. Browne publishes 

 a second contribution to our knowledge of the anatomy of the cone 

 and fertile stem of Equisetum. The summary of her results states 

 that: — 1. The xylem of the axis of the cone of E. maximum is more 

 reduced than that of E. arvense and E. palustre, but less so than that 

 of E. limosum. 2. The cones, with wider steles, have, on the whole, a 

 more reduced vascular system, as though the reduction in width of 

 stele had not kept pace with the reduction in number of elements 

 lignified. 3. The reduction of xylem is manifested by the persistence of 



* Univ. Geneve. Inst. Bot. Prof. Chodat, ser. 8, fasc. xii. (1914) 42 pp. See 

 also Bot. Centralbl., cxxviii. (1915) pp. 359-61. 



t Ann. Bot., xxix. (1915) pp. 231-64 (3 pis. and 5 figs.). 



