Anatomie. 179 



dermal pockets'' by a bridge of one or two cells with endo- 

 dermal markings. Small groups of tracheides are sometimes 

 to be found among the Clements of the pith which may or may 

 not have a connection with the xylem ring. 



The seedling of Schizaea piisilla was also examined by 

 the author and also two specimens of a small form of 6". dlcho- 

 tonia which were probably seedling plants. The xylem in the 

 basal region of thesc plants is first of all solid; at a point 

 higher up a mass of parenchyma appears in the centre, but 

 no internal phloem is to be found at any point throughout the 

 transitional region. The vascular bundles of the petiole are 

 collateral. The protoxylem Clements occur on the adaxial side 

 of the xylem, but they are not prolonged down into the stem. 



Although the author considcrs that the internal tracheides 

 and the internal endodcrmis are vestigial structures, yet he 

 does not acccpt Jeffrey's Suggestion, that the vascular System 

 of Schizaecu is derived from a dialystelic type (i. e. one with 

 phloem on both sides of the xylem). On the other band, it 

 is maintained that it owes its typical structure to reduction from 

 a medullated stcle with an inner endodcrmis, and that neither 

 Schizaea nor its anccstors ever possessed any internal phloem. 

 In the general part of the paper the author summarises and 

 discusses the relative importance of the different kinds of evi- 

 dence available for the settlement of the qucstion of reduction 

 or advance. The general theory of the bündle System of the 

 petiole is also discussed, and the author supports the view that 

 the centrally placed parenchyma in a closed leaf trace, such as 

 those of certain Gleichenlas, is to be regarded as historically 

 non-vascular tissue. Finally some of the recent views regar- 

 ding the stcle and the morphology of tissucs are referred to 

 and criticised. D. J. Gwynne-Vaughan. 



BOODLE, L. A, On Descriptions of Vascular Struc- 

 tures. (The New Phytologist. Vol. II. 1903. Nos. 4 and 5. 

 p. 107.) 



It is shewn how, according as one describes the vascular 

 and other tissues of a stem as traced upwards or downwards, 

 one is easily led to use phrases which commit one to a diffe- 

 rent opinion as to their morphological nature in the two cases. 

 The writer then illustrates the ease with which the central 

 portions of the xylem of a protostele may become at need 

 replaced by parenchyma so as to form a more or less definite 

 pith, as in some Hymenophylliims and in roots of many Mono- 

 cotyledons. For this and other reasons it is held more pro- 

 bable that a dictyostele together with the parenchyma at its 

 centre and that forming the leaf-gaps should be regarded as 

 the morphological equivalent of the protostele, rather than that 

 an intrusion of the cortex into the stele should have taken 

 place. Again, it is highly probable that many advances in 



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