258 Anatomie. 



da eine Züchtung auf Verminderung der Zellgrösse auch eine Ver- 

 minderung des Ertrages zur Folge hat, nur eine Auslese gross- 

 zelliger Formen in Frage kommen. Sierp. 



Sahni, B., The Anatomy oi Nephrolepis volubth's ]. Sm., with 



remarks on the Biology of the genus. (New Phytologist. 



XIV. Nos 8—9. p. 251—274, with PI. IV and 7 figs. in the text. 1915 ) 



Nephrolepis volubilis has an unusual habit; the main axis gives 



rise to very long stolons that instead of creeping on the ground 



Scale trees ot considerable height, bearing aloft the young plants 



produced on them. These primary stolons bear short branches or 



secondary stolons; these bend sharply upwards and constitute the 



Short axis of the daughter plant. The latter consists of a tuft of 2 



to 4 leaves and a number of wiry unbranched stolons coiling round 



adjoining petioles and serving as climbing organs. 



None of the available daughter-plants showed any trace ot 

 roots and their absence is easily understood since the plants exa- 

 mined were still attached to the stolons and therefore in communi- 

 cation with the absorbing- System of the parent plant. 



The Stele of the primary stolon is exarch; the metaxylem is 

 scalariform and extends to the centre of the stem, but is traversed 

 by tortuous chains of thin-walled parenchymatous cells. There are 

 7 to 9 protoxylems, each traversed by 1 or 2 longitudinal bands of 

 parenchyma. The phloem is continuous round the xylem. The en- 

 dodermis is also continuous and some of its cells are traversed 

 radially by peculiar struts. The anatomy of the secondary stolons 

 is essentially similar to that of the primary ones, though the tissues 

 are smallen From 1 to 3 protoxylems pass out from the primary 

 to the secondary stolons. One of these, the median one when there 

 are 3, is devoted entirely to supplying the branch; the others when 

 present give off branches into the secondary stolon, but are also 

 continued into the main stolon. 



The branches that depart from the main axis of the daughter- 



plant never leave gaps. The central cylinder, however, becomes 



horseshoe shaped „by the invagination of the cortex which pushes 



the endodermis pericycle and phloem before it." The dorsal Strands 



of the first two leaves are cut off from the two sides of the stele 



and come to lie opposite the invagination to which they do not 



contribute. In the daughter plants all the traces are Compound. 



Eventually the invagination breaks through the horseshoe and di- 



vides it into two large curved Strands; each of these cuts off Strands 



that contribute to the formation of the first two leaf-traces. Before 



the axial xylem becomes again continuous the dorsal Strand ot the 



third leaf-trace arises, causing a distinct gap and is followed in 



its outward course by two adaxial lateral Strands. A fourth leaf 



soon arises in a similar way and the young plant becomes dictyostelic. 



In the petiole the three bundles of the leaf-trace are subject to 



a certain number of anastomoses; the two adaxial lateral bundles 



become crescentic and the dorsal one anastomoses twice to thrice 



with each lateral one before becoming absorbed into one of these. 



These two crescentic Strands eventually become fused by the adja- 



cent horns of each crescent and produce a T-shaped Strand, the stalk 



of the T facing abaxially. This structure, which occurs near the tip 



of the leaf, recalls that of the petiole of Lygodium. The stele of 



the stolon also recalls that of the stem of Lygodium. 



