550 SUMMARY OF CURRENT RESEARCHES RELATING TO 



other ferns than as a guide to a systematic arrangement of the order itself. 

 The present work makes a special study of the rhizome in this respect. 

 The author gives a short resume of former work by Mettenius, Russow, 

 Prantl and others. As regards nomenclature, he follows Hooker's 

 ' Synopsis Filicum,' except that Loxsoma is now by common consent re- 

 moved from Hymenophyllacese to Davalliacese. The structure of the 

 Thizome is then described as it occurs in the two genera Trichomanes and 

 HymenophyUum. Trichomanes is distinguished by the following char- 

 acteristics : (1) " Deckzellen," either at the junction of the sclerenchyma 

 and the peripheral parenchyma, or, where this is absent, in contact with 

 the epidermis ; (2) tracheids of the xylem are similar almost through- 

 out, and arranged equally in all directions when seen in tranverse 

 section. The genus is divided into two groups, the first characterised 

 by : (1) an elliptic and 3-sided transverse section of the rhizome ; 

 (2) the black colour of the peripheral sclerenchyma in quite mature 

 (dried) specimens ; (3) semi-parenchymatous tissue between the scleren- 

 chyma and the bundle-sheath ; (4) the eccentric collateral bundle ; 

 xylem consisting of some few tracheids ; preponderance of phloem in 

 the bundle. To this group belong 19 species, which are all small and 

 delicate, and possess other morphological features in common. 



The second group has (1) a circular transverse section of the rhizome ; 



(2) yellow, yellow-brown to reddish coloration of the sclerenchyma ; 



(3) central concentric bundle ; preponderance of xylem, which forms 

 a circle in the bundle ; phloem forms a ring in tranverse section. To 

 this group belong 27 species, of sturdy growth, mostly erect, sometimes 

 having a much shortened rhizome and long-stalked fronds. 



The genus HymenophyUum is characterised as a whole by : (1) absence 

 of "deckzellen" ; (2) tracheids of the xylem of two kinds, symmetrically 

 arranged ; (3) unequal development of the circular tranverse section of 

 the rhizome ; (4) closely adpressed, yellow, yellow-brown or reddish 

 sclerenchyma-cylinder ; (5) central, concentric bundle. There is a pre- 

 ponderance of phloem in the bundle. Four different types of xylem 

 occur in the transverse section, and on this character the genus is 

 divided into four sections ; (a) ring-shaped xylem ; (b) horse-shoe shaped 

 xylem ; (c) fan-shaped xylem ; (d) irregular, mostly much reduced, xylem. 

 Among these four groups are distributed the 52 species of Hymeno- 

 phyUum, as well as four so-called species of Trichomanes. The author 

 refers to many specimens in the Yienna herbarium. The paper is illus- 

 trated by text-figures and plates. 



Boodle, L. A. — Secondary tracheids in Psilotum. Preliminary account. 



New Phytohgist, iii. (1904) pp. 48-9. 

 Bower, F. O. — Ophioglossum simplex Ridley. 



[Anatomy of a new species from East Sumatra.] 



Annals of Botany, xviii. (1904) pp. 205-16 (1 pi.) 



Carestie — Localites nouvelles pour le Jura occidental: Aspidium auriculatum, 

 Asplenium lobatum. (New localities for the western Jura for these two ferns.) 



Arch. Flore Jurass., iv. (1903) p. 84. 



Chandler, S. E. — On the arrangement of the vascular strands in the "seedlings" 

 of certain leptosporangiate Ferns. Preliminary notice. 



New Phytohgist, iii. (1904) pp. 123-5 



