ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 575 



than the other. In L. complanatujn a short strand from the main stele 

 passes into the foot, and the peripheral cells of the foot retain the 

 appearance of an absorptive tissue after the disappearance of the pro- 

 thallns. The arrangement of the vascular tissues at the base of the stem 

 shows much irregularity, but the xylem appears to be continuous with 

 that of the first root. In the lower part of -the stem the xylem strands 

 take a very irregular course, fusing and sub-dividing. The upper part 

 of the stem shows a tri- or tetr-arch arrangement of xylem with central 

 metaxylem, generally connected with two or more groups of protoxylem. 

 The apex is occupied by several large actively dividing cells. The 

 stem branches dichotomously, one branch being generally weaker than 

 the other, or by retardation forming a pseudo-adventitious bud in 

 L. complanatum. The first leaves are scale-like, unveined, and spirally 

 arranged. The later leaves have a vascular strand of a few narrow 

 tracheids surrounded by thick-walled bast. 



Vascular System of Hymenophyllacese.* — A. G-. Tansley prints the 

 third of his lectures on the evolution of the Filicinean vascular system, 

 noting first the approximate parallelism of development between vas- 

 cular and sporangial characters in the Leptosporangiate Ferns. Among 

 Bower's Simplices we have almost exclusively protostelic and soleno- 

 stelic forms ; the Gradatse include the protostelic Hymenophyllacea3, 

 but are of the most part solenostelic ; among the Mixtse are included 

 the great mass of dictyostelic types. The author then discusses the 

 Hymenophyllacefe, whose unilamellate fronds, he is inclined to think, 

 have been derived, as in Todea and Asplenium, from fronds of the 

 normal type with stomata and intercellular spaces. The sori and 

 sporangia are of a relatively primitive type. The vascular system is 

 on the whole simple, and, while the characters of the simplest forms 

 are undoubtedly due to reduction, there is ground for supposing that in 

 the median types occur really primitive features which are shared by 

 the Botryopteride^e. Such a median type is found in Trichomanes 

 reniforme and certain species of Hymenophyllum. After treating the 

 various types in detail, he concludes that this median type is probably 

 nearly primitive for the Ferns, and is unhkely to be a much reduced 

 form. Moreover, the marked dichotomy in the branching of the 

 Hymenophyllaceous pinnae may also be considered a primitive feature 

 retained by many members of the family. 



Wounds in Calamites.f — M. C. Stopes describes some instances of 

 the formation of callus wood in wounded Calamites preserved in three 

 slides in the fossil collection of the Manchester University Museum. 

 In both cases the wound was so deep as to pass through the vascular 

 cylinder and reach the pith, and the formation of new tissue curved 

 round the open ends of the broken ring and formed a quantity of wood 

 in the pith-cavity in inverse orientation to the normal strands. 



American v. European Pteridology.J — L. M. Underwood demon- 

 strates that Wooclwardia paradoxa, a fern from British Columbia recently 



* New Phytologist, vi. (1907) pp. 109-20 (figs.), 

 t Ann. Bot., xxi. (1907) pp. 277-80 (1 pL). 

 X Torreya, vii. (1907) pp. 73-6. 



