Anatomie. — Morphologie etc. 259 



The author also describes the branching ot the rhizome of N. 

 yamosa Moore. In the rhizome the stele consists of two long, cur- 

 ved Strands of xylem each surrounded by phloem, pericycle and 

 endüdermis and facing one another. The parenchyma between them 

 represents the continuation of the long leafgaps. When a branch 

 is about to be produced the leafgap on that side closes, the bund- 

 les fusing by their margins. The arc of xylem thus formed passes 

 out as the branch trace, leaving once more two curved Strands 

 facing one another. At first the branch trace is a horse-shoe, con- 

 cave adaxially^ but soon the opposite side of the stele opens and 

 the internodal structure of the main axis is established in the branch. 

 The leaf-trace originates in a manner almost identical with this, 

 except that the abaxial division of the C-shaped Strand is onl}' a 

 temporary phase if it is attained at all. 



.V. altescandens (CoUa) Baker resembles N. nunosa in essen- 

 tials, but the two curved Strands of the internode remain separate 

 at the formation of the leaf-trace and each abstricts a small Strand. 

 The trace is thus bifascicular at its origin. but the two bundles fuse 

 in the petiole. The author considers that from the biological point 

 of view Nephrolepis volubilis bears out S per lieh 's view of the 

 origin of epiphytism in the genus, viz; that the initial stage of the 

 emancipation of plants from the soil was the possession of stolons. 



Brongniart and later Trecul held that the stolons oi Ne- 

 phrolepis were root-like in nature, but other writers, chiefly^ Lach- 

 mann, Goebel, Poirault, Sperlich and Heinricher appear 

 to have established the view earlier held by Ku nze, Hofmei ster 

 and Russow that the stolons were cauline. In 1905 Velenovsk}^ 

 claimed them as „Achsenträger" or an organ sui gen eris , a view 

 that he defended against considerable adverse criticism in 1913. 

 The present investigations appear to confirm the cauline nature of 

 the stolon. 



The author holds that phylogeneticall}^ Nephrolepis shows a 

 distinct tendency towards the adoption of epiphytism. This ten- 

 dency seems to have developed along two man lines. Starting from 

 a hypothetical solenostelic form with a short erect stock and simple 

 leaf-traces one series seems to have developed as a scandent rhi- 

 zome bearing distant leaves and showing elaboration of the trace; 

 the other, also showing complication of the trace, seems to have 

 developed a highly specialised structure, the stolon, having appa- 

 rently a primitive anatomy. 



Isabel Browne (University College London). 



Dahlgren, K. V. Ossian, Zytologische und embr3'^ologi- 

 sche Studien über die Reihen Pri)nulales und Plunibaginales. 

 (Kgl. svenska Vet.-Ak. Handl. LVI. p. 3—80. 3 T. 137 F. 1916.) 



Der Verf. hat vergleichende Untersuchungen über die beiden 

 Blutenformen von Prinnüa officinalis gemacht. An welchem Stadium 

 der Pollenbildung der Grössenunterschied zuerst sichtbar wird, 

 konnte er nicht entscheiden, zur Zeit der heterotypischen Teilung 

 ist aber dieser Unterschied sehr deutlich. In Bezug auf den Chro- 

 mosomenbestand konnte er keine Differenz zwischen den beiden 

 Formen entdecken. In Bezug auf die Anzahl der Samenanlagen 

 fand der Verf. einen weit geringeren Unterschied als andere Verf.: 

 er zahlte bei der brevistylen Form durchschnittlich 61,04, bei der 

 longistylen 57,22 Samenanlagen. In den Grössenverhältnissen der 



