50 SUMMARY OF CURRENT RESEARCHES DELATING TO 



collected in Sarawak by J. Hewitt. He describes the structure of the 

 rhizome, the bifurcation of the rhizome, the anatomy and morphology 

 of the frond, the root, node and protoxylem. He states reasons for 

 rejecting E. B. Copeland's separation of the species from Matonia and 

 placing it in a new genus Phanerosorus. 



Centripetal Xylem in Equisetufti.* — A. J. Eames treats of the 

 occurrence of centripetal xylem in Equisetum. In summing up his con- 

 clusions he states as follows. In Equisetum the development of the 

 xylem of the vegetative stem is centrifugal throughout. The internodal 

 bundle does not consist of three united bundles, but is a unit in struc- 

 ture representing the much reduced internodal primary bundle of the 

 Calamites. The axial bundles of the strobilus show conditions inter- 

 mediate between those in the vegetative stems of the Calamites and of 

 Equisetum. The vegetative leaf -trace does not arise solely from the 

 protoxylem-strand of the internodal bundle, but from all three parts of 

 the xylem. The discovery of cauline centripetal wood in Calamites 

 petfyciirensis Scott affords a link between Equisetales and Sph en ophy Hales 

 and possibly with the Lycopodiales. Centripetal wood was doubtless 

 well developed in the most primitive Equisetaceous forms, but disappeared 

 early in the history of the series. Yet this ancestral character survives 

 in the leaf-trace. (This conservatism for ancestral characters makes 

 the leaf-trace of great value in questions of phylogeny.) Centripetal 

 wood is now known to exist in all the large groups of Vascular Crypto- 

 gams. The formation of xylem adaxially from the protoxylem is a 

 cryptogamic character. Bundles containing both centripetal and cen- 

 trifugal xylem are not characteristic of any one group of Vascular 

 Cryptogams, as, for example, of the ferns, nor in the higher plants can 

 they be of other phylogenetic value than as indicating general crypto- 

 gamic affinities. 



Imbedded Antheridia in Dryopteris and Nephrodium.f — C. A. Black 

 gives a resume of recent papers by Farmer and Digby, by Lang and by 

 Yamanouchi, on apogamy in ferns, and details her own investigations 

 as to the development of the imbedded antheridium in Dryopteris stipu- 

 laris and Nephrodium molle. In brief her results are that she found 

 no apogamy in either species, although she repeated the cultural condi- 

 tions of Yamanouchi. On many of the prothallia she found an imbedded 

 antheridium similar to those of lower ferns. In D. stipularis she found 

 in addition some deep-seated structures, half of which consisted of 

 sperms and the remainder of large cells. In Nephrodium molle a deep- 

 seated egg- and ventral canal-cell were found. 



Prothallium and Embryo of Danaea.ij: — D. H. Campbell publishes 

 a preliminary note on the prothallium and embryo of Dansea, after 

 studying a fine series of specimens of D. Jenmanii, D. elliptica and 

 D.jamaicensis, obtained in Jamaica in July 1908. He briefly indicates 

 the characters of the prothallium, the archegonia and antheridia, and the 

 embryo with its early cell-divisions and rudimentary organs. 



* Ann. Bot.,xxiii. (1909) pp. 587-601 (pi.). 



t Bull. Torrey Bot. Club, xxxvi. (1909) pp. 557-71 (3 pis.). 



\ Ann. Bot., xxiii. (1909) p. 691. 



