LFCOPODIA CE.E. ^ 1 j^ 



and Sphagnum), in the anodal direction, and thus produce rows of segments 

 arranged spirally. 



In Lycopodiwn clavatum, finally, the same authorities thought they recognised a 

 small apical cell, but were uncertain whether it was two- or four-faced. Pfeffer, 

 on the other hand (as he informs me in a letter), did not find an apical cell in 

 either Z. clava/ufji, annotiniim^ or ChamcEcyparissus ; and Cramer's experience was 

 the same with Z. Selago. The dichotomy begins in this case by two small-celled 

 papillae rising on the flat apex of the shoot, and growing up into the two shoots 

 of the dichotomy. 



The gemmce or bulbils of Z. Selago, which subsequently fall off, are probably 

 products of the leaves, not of the stem ; they are apparently axillary. It appears 

 however to result from Cramer's description and drawings that they spring from 

 the basal part of the leaf itself— at least this is indicated by the circumstance that 

 the vascular bundle does not spring from the cauline but from the foliar bundle. 

 The additional circumstance that sporangia are developed on the earlier leaves of a 

 year's growth, bulbils on the later ones (the branch continuing to grow for years 

 without dichotomising), appears further to justify the supposition that the bulbils 

 occupy morphologically the same position as the sporangia, which in Lycopodium 

 unquestionably originate from the leaves, and are not axillary. 



The Roots of Lycopodiacece show very remarkable morphological peculiarities ; 

 they are the only roots at present known the branching of which is (apparently or 

 actually) dichotomous ; the successive dichotomies lie in planes crossing at right 

 angles. A second peculiarity are the Rhizophores of Selaginella and the root-like 

 shoots of Psilotum. All these phenomena have been investigated by Nageli and 

 Leitgeb (/. c). 



Psilotum triqucirum is a plant perfectly destitute of roots, forming however a 

 number of underground shoots which serve the purpose of roots and are extremely 

 similar to them. On the shoots of the rhizome which approach the surface of the 

 ground may be detected with a lens minute leaves of a whitish colour and acicular 

 shape ; the deeper root-like shoots have a blunter end, on which no trace of leaves 

 can be detected, even with the lens. While the anatomical structure of the super- 

 ficial shoots corresponds to that of the true stem of these plants, in these deeper 

 shoots the vascular bundles are united into an axial group, as in true roots. The 

 shoots which bear visible rudiments of leaves may turn upwards, become green and 

 transformed into ordinary foliage-shoots, while the root-like shoots, which are more 

 slender, may also turn upwards, become thicker, and assume the appearance of 

 the ordinary superficial rhizome-shoots. In this point therefore they differ at once 

 from true roots, but still more in the absence of a root-cap. They terminate in an 

 apical cell, which forms oblique segments alternating in different directions. The 

 most important point, however, is that these shoots really possess rudiments of leaves 

 which consist of only a few cells and do not project above the surface, but remain 

 concealed in the tissue. They are best recognised in longitudinal section, when 

 they are seen to consist of an apical cell and from two to five cells with the 

 characteristic arrangement of leaf-cells. Similar rudimentary leaves consisting of 

 but few cells occur also on the ordinary rhizome- shoots, where, however, they do 

 not undergo further development, especially when the end of the shoot appears 



