282 



PRIMARV ARRANGEMENT OF TISSUES. 



corners is smaller than that of the rows of leaves : in L. Selago, e. g. with whorls of five 

 members (that is ten rows), there are 4-6, in L. inundatum with f arrangement of the 

 leaves 4 or 5, in the above-mentioned branches of L. alpinum 3, &c. From Hegelmaier's 

 statement that in the main vegetative axes of L. clavatum and L. annotinura, with a diver- 

 gence of f, -^j, ^, there were found 10-17 corners, it would appear that there is a higher 

 number of corners than of rows of leaves. 



Where the rows of leaves correspond exactly to the corners, all the bundles of one row 

 of leaves insert themselves on the same corner. In other cases one corner may take up 

 bundles from one row only, but must also often take them from more than one row. 

 Usually it only takes up the bundles of two neighbouring rows, but sometimes also single 

 bundles of more distant rows'. The bundles insert their inner end irregularly, some- 

 times on the right, sometimes on the left, and sometimes on the inner side of the next 

 lower bundle. 



Sect. 78. Selaginella. A number of species, forming no doubt the majority, 

 such as S. Martensii, S. helvetica, pubescens, rupestris, &c., have in each shoot one 

 axile, ribband- or plate-like vascular bundle, the faces of which in relation to the 

 ground are directed upwards and downwards, while the margins are lateral to the 

 right and left : in some, as S. pubescens, the bundle is provided at the middle line of 



its under surface, and near to each 

 lateral margin with a sharp band-like 

 process. The leaves have each one 

 small bundle, and these behave in 

 their course and insertion one on 

 another, and also on the cauline por- 

 tion, similarly to the leaf-bundles of 

 Lycopodium. SThey are inserted on 

 the bundle at its margins : in the 

 species with two double rows of 

 leaves, one facing towards each side, 

 the bundles of the two corresponding 

 rows (that is those from one row of 

 upper and one of lower leaves) insert 

 themselves on each lateral margin : in 

 S. rupestris with leaves in many rows, 

 the bundles of several rows pass to 

 each margin. S. Kraussiana,Galeottii^ 

 and most other articulatse ' have, in- 

 stead of one axile bundle, two which 

 run near the middle line, each follow- 

 ing one double row of leaves : each 

 takes up the leaf-bundles on its own 



Fig. i3[,— Selagfinella inEequalifolia ; transverse section of the • j • i p ji 



stem (150). From Sachs' Textbook. SIQC, VIZ. thOSC irOm OUC UppCr and OHB 



lower row of leaves, at its outer margin, 

 with the same arrangement, as in the first-mentioned series of cases. 



' Compare Cramer, Lc. p. 14, Taf. 30, 31. 



= Nageli, Beitr. /. c. p. 53.— Hofraeister, Vergl. Unters. 



^ A. Braun, Monatsbr. d. Berliner Academle, 27 Apr. 1865. 



