274 SUMMARY OF CURRENT RESEARCHES RELATING TO 



to be regarded as an expression in miniature of what is found in full- 

 sized rhizomes, and is to lie explained on physiological, rather than on 

 phylogenetic, grounds. 11. The segmental construction of the rhizome 

 is more or less clearly reflected in the stelar anatomy. 12. Comparisons 

 are made with the Zygopterideas and Cycadofilices as regards the outer 

 and inner xylems, the secondary thickening, the peculiarities of the 

 leaf-trace, and the nature of the branching, and confirm the general view 

 of a relationship between the Ophioglossaceae and the more primitive 

 ferns. 



Rhizome of Platycerium.* — Miss Harriet E. Allison gives a de- 

 tailed and illustrated account of the vascular anatomy of the rhizome of 

 Platycerium, and finds that it suggests a comparison with the Maratl iaceae 

 and Pteridea;. Most likely Platycerium is related to the Matonineae. 

 Diels placed it near Cheiropleuria ; and Christ groups these closely with 

 Dipteris. But anatomically Dipteris is relatively simple ; its simple 

 solenostele is replaced by several concentric solenostelic cylinders in 

 Mat on i<i. Platycerium might be regarded as the dictyostelic type of a 

 series of which Dipteris and Matonia are the solenostelic type's. And 

 possibly facts other than anatomical may be discovered to support the 

 supposition that Platycerium is more or less allied to the Dipteris- 

 Matonia series. 



Morphology of Isoetes.f — W. H. Lang has been studying the 

 morphology of Isoetes, and gives an account of the general structure of 

 the stock of Isoetes lacustris. In summing up his results he states that 

 it consists of a shoot-region and a rhizophoric-region. The origin of 

 the rhizophore may perhaps stand in some relation to the deep-seated 

 secondary meristem at the base of the shoot. Once initiated, however, 

 the growing region of the rhizophore behaves like a primary apex which 

 is congenitally sunken and enclosed. This apex is extended as a line in 

 two-lobed forms, and in three or four directions in three or four-lobed 

 stocks. It gives rise to roots in acropetal order, and these when mature 

 stand exogenously on the surface, which is exposed by the split. On 

 this general view (which allows for the conflicting facts emphasized in 

 Yon Mohl's and Hofmeister's explanations respectively, and confirms 

 Williamson's comparison with the organization of the Lepidodendreas), 

 some details of the stock of Isoetes will be further investigated by the 

 author. 



Vegetative Reproduction in Selaginella.J — Miss N. Bancroft has 

 investigated the reproductive tubers in two Indian species, SelayineUa 

 chrysocaulos andi& chrysorrhizos. The tubers are fundamentally similar, 

 though differing for physiological reasons owing to difference of position 

 on the plant. In S. chrysocaulos they occur at the ends of ordinary 



* New Phytologist, xii. (1913) pp. 311-21. 



t Mem. and Proc. Manchester Lit. and Phil. Soc, lix. (1915) No. 3, pp. 1-28 

 (figs.). 



% Ann. Bot., xxviii. (1914) pp. 685-93 (1 pi. and figs.). 



