672 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



r Structure and Affinities of Dipteris.* — A. C. Seward and Eliza- 

 beth Dale give a general account of the synonymy and characters of 

 the four species of tbis genu?, which is mainly of Indian and Malayan 

 distribution. They also give an elaborate description of the anatomy 

 of rhizome, root, and leaf in Dipteris conjugata, and then proceed to a 

 discussion of the systematic position of the genus. " The anatomical 

 features, taken in conjunction with the sporangial characters and the 

 characteristic form and venation of the fronds, afford ample reasons for 

 the removal of the genus from the Poiypodiacefe, and its inclusion in a 

 separate family, of which it represents the solitary surviving- type." 

 The family had a wide European distribution in the early Mesozoic 

 period. The authors give a tabular account of the distribution in space 

 and time of the probable members of the Dipteridineas. 



Danish Pteridophyta.f — C. Christensen publishes a revised list of 

 the Danish Pteridophytes, with a few critical notes. He recognises 

 46 species. 



Brazilian Ferns.J — H. Christ concludes his study of the ferns of 

 South Brazil and treats of the species falling under the following 

 genera— Osmunda, Gleichenia, Schizsea, Aneimia, Dansea, Ophioglossum, 

 Botrychium, Lycopodium. The total number of species in the paper 

 is 288. Eight of these are described as new in the concluding instal- 

 ment, and with them are some new varieties. 



Hybrid Origin of Asplenium ebenoides.§ — M. Slosson has been 

 endeavouring for some years to obtain plants of Asplenium ebenoides 

 by experimenting with the prothallia of A. platyneuron and Camptosorus 

 rhizophyllus, and has now obtained young plants so like those produced 

 naturally that she claims to have proved her case. She describes the 

 methods followed in dealing with the prothallia and the precautions 

 adopted. 



Nature of the Stele of Equisetum.|| — D. T. Gwynne-Vaughan 

 finds that the usual comparison of the vascular bundles of Equisetum 

 with those of a monostelic phanerogam cannot be satisfactorily main- 

 tained. The xylem of the so-called vascular bundle of Equisetum con- 

 sists of three strands, two of which are lateral and cauline, while the 

 median or carinal strand is common to stem and leaf. The fact that 

 only a small part passes out as a leaf-trace, and not the bundle as a 

 whole, is an essential point of difference from the bundle of a seed- 

 plant. The development of the tracheids in the leaf-trace and the 

 carinal strand are not exarch but endarch or perhaps slightly mesarch 

 on the adaxial side. The lateral strands are differentiated later than 

 the carinal strand, but do not seem to be a continuation of its centri- 

 fugal development. It is suggested that the lateral xylem strands in 

 the vascular bundles of existing Equisetums may perhaps be taken to 

 represent the last remnants of a primitive central mass, and that this 



* Phil. Trans. B, cxciv. (1901) pp. 487-513 (3 pis.). 



t Bot. Tidskr., xxiv. (1902) pp. 369-76. 



% Bull. Herb. Boiss., ii. (1902) pp. 6S9-70S. 



§ Bull. Torr. Bot. Club, xxix. (1902) pp. 487-95 (with figs, in text). 



|| Rep. Brit. Ass., 1901 (1902) p. 850. 



