276 



STIGMARIA. 



of all the cell-walls. In Hooker's 1 figure no such differentiation of the 

 layers is apparent ; the wood-strand here lies excentrically inside a per- 

 fectly uniform mass of tissue. Whether all these variations point to 

 specific distinctions between the specimens which have been examined 

 cannot unfortunately be at present determined. 



The character and outline of the central wood-strand are not found to 

 be exactly the same in all transverse sections. A careful consideration of 

 the differences which here present themselves is the more necessary, because 



Renault in reliance upon 

 them has arrived at some 

 important conclusions, to 

 which we shall have to re- 

 cur more than once in the 

 succeeding pages. The 

 cases to be distinguished 

 are chiefly three. First of 

 all, there are the append- 

 ages in which the transverse 

 section of the bundle show- 

 ing secondary increase has 

 the corresponding form of 

 an isosceles triangle (Fig. 

 ), such as we have be- 



FIG. 34. Stigmaria. Transverse sections of the wood-bundles of the 

 appendages. ./ collateral bundle with secondary increase of the kind 

 first described. B, C, D bundles of the forms of the second category. 

 B of the ordinary normal kind, C much reduced, D with secondary 

 increase. E bundle of the third kind considered by Renault to be 

 a march root-strand. At a the evident initial strand, about which 

 there can be no question, at b the places which Renault inclines to regard 

 also as initial strands. All after Williamson (6) and (1), xl. 



fore observed in the trace- 

 bundles in the wood and 

 rind ; only the mass of the 

 normal wood traversed by 

 fascicularrays is smaller, the 

 angle at the point of the 

 triangle is less acute. That 

 the bast-zone, when pre- 

 served, is to be found at its 

 base, I have satisfied myself 

 from a preparation in the 



Botanical Department of the British Museum. Renault 2 has figured a 

 transverse section of this kind with remains of bast ; figures showing the 

 ordinary condition will be found in Williamson 3 and Renault 4 . 



Secondly, there are appendages of a different habit (Fig. 34 B, C, D), 

 figured by Williamson 5 on the same tables as the preceding, in which the 

 wood-strand is composed of an ovate group of tracheides wide on trans- 



1 Hooker (4), fa, f. a. a Renault (10), t. i, f. 4. 



4 Renault (2), vol. i, t. 20, ff. i, 8, and vol. iii, t. A, ff. I, 3, 5, 7. 



s Williamson (6), tt. 9, n. 

 8 Williamson (6). 



