8 Miss Robertson, Notes on the Anatomy of 



pricks in the brown substance, to comparatively large spheres, 

 whose mutual contact reduces the brown substance to a mere 

 reticulum. It is interesting to meet with such appearances in the 

 cells of a recent Cycad, as they closely resemble some that have 

 been described and figured by Seward 1 in the ground tissue of the 

 petiole of Gycadeoidea gigantea. The author points out that 

 these frothy and granular cell contents bear a deceptive resem- 

 blance to the spores or cells of an endoparasitic organism, and 

 mentions similar occurrences in recent plants, referring especially 

 to the vacuolated cell contents found by Professor Marshall 

 Ward 2 in the parenchymatous tissues of some of the Rubiaceae of 

 Ceylon. 



The pericycle and the tissue between the primary and secondary 

 phloem contains a great many cells whose extremely thick, 

 beautifully stratified, lignified walls are traversed by numerous 

 branching pits. (Fig. 3.) 



The many-layered periderm of thin-walled cells, which at this 

 stage forms the outermost layer of the root, seems to arise in the 

 pericycle. The phellogen gives rise to very little tissue internal 

 to itself. 



Another more slender root, of which only the base remained, 

 was found to be triarch. 



(vii) Anomalous Periderm of Root and Stem. 



As the references to this subject in the literature are rather 

 scanty and scattered, it may be well here to bring together some 

 account of the results hitherto obtained. 



In fossil Cycadaceous plants the formation of anomalous 

 periderms has attracted more attention than in their modern 

 representatives. Solms-Laubach 3 in a paper published in 1892, 

 points out that in the case of a section of Bennettites Peachianus 

 figured by Carruthers 4 , the structures in the pith which were at 

 one time compared to the " star-rings" of some Medulloseae, are 

 really cork formations. He shews that some medullary periderm 

 can also be recognised in Bennettites Gibsonianus, and in the pith 

 of a specimen of Gycadeoidea Mantelli, Solms, from the Isle of 

 Wight, of which he was able to examine a small fragment, innu- 

 merable little peridermal rings were found, each with a gum canal 

 in the centre. Gycadeoidea Ferrettiana and G. Gapelliniana 

 offered a more abundant rhytidome formation in the interior of 

 the trunk. The transverse section of the pith of the first shewed 



1 Q. J. Geol. Soc. Vol. mil 1897, p. 26. 



2 Fossil Plants, Seward, 1898, fig. 41 b, p. 214. 



3 Solms-Laubach and Capellini, "I Tronchi di Bennettiteae dei Musei Italiani," 

 Mem. d. Real. Ace. d. Sci. d. Instit. d. Bologna, Ser. v. Tom. n. 1892. 



4 Trans. Linn. Soc. Vol. xxvi. 1870, Plate lxii. fig. 2. 



