ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 187 



Localisation of Daphnine in Daphne Laureola.* — W. Russell finds 

 that the glucoside daphnine is localised, in the stem and leaf of the 

 plant, in the epidermis, in the parenchyma and in the fibres of the 

 primary bast ; in the secondary bast it occurs in these elements and 

 also in the medullary rays ; in the wood it occurs in the medullary rays. 

 The root, which is rich in starch, contains but little of the glucoside ; 

 the author detected it in the periphery of the cortex, and in the bast 

 of young roots, but was not able to certainly recognise it in old roots. 

 All the members of the flower contain it, its distribution resembles that 

 in the foliage leaves, but it predominates in the epidermis. It also 

 occurs in the integuments! of the ovule and in the nucellus in the neigh- 

 bourhood of the chalaza. The glucoside can easily be made to crystallise 

 in situ, by placing leaf or stem in alcohol and tartaric acid for 24 hours 

 with subsequent evaporation. The crystals are grouped in roundish 

 masses and show the radiating arrangement which is observed in sphero- 

 crystals of inulin. Daphnine is always accompanied by oily matters. 



Structure and Development.]! 

 Vegetative. 



Evolution of Vascular Tissue.f — W. C. Worsdell gives a short 

 general survey of the various types of arrangement of the vascular tissue 

 in plants and suggests a course of evolution of the types characteristic 

 of the higher plants from those found in the lower. The prototype 

 is sought in the solid stele (protostele) consisting of a central mass of 

 xylem surrounded by a ring of phloem. This structure always appears 

 as the first stage in the individual development in the fern group, and 

 also in the mature vascular structure of several of the most primitive 

 ferns such as Hymenophyllacese and, among the fossils, Botryopteris. In 

 the next stage a pith arises in the centre of the solid stele ; examples 

 occur in Platyzoma (Gleicheniacege), Schiscea, and others. The proto- 

 xylem is situated at, or a short distance within, the periphery of the 

 metaxylem, the development of which is chiefly centripetal. In the third 

 stage, the solenostele, an internal zone of phloem is added, as in various 

 SchizseaceEe, and Medullosa stellata among the Cycadofilices. The next 

 condition, the dialystelic, results from the splitting of the solenostele 

 into a number of solid steles or concentric strands, the protoxylem being 

 still at or near the external limits of the xylem. This structure is due 

 to the crowded arrangement of the leaves in the stem, necessitating 

 frequent gaps in the original solenostele, to allow of the passing out of 

 the leaf-trace bundles. Both conditions belong essentially to the siphono- 

 stelic or tubular type of stele. Dialystely is very common in ferns, 

 occurring in almost all the Polypodiaceae which represent the most 

 advanced type of the series. It also occurs in several of the Cycado- 

 filices, such as the Medullosse and Cladoxylon. The gymnospermous 

 type arose by the gradual reduction of the concentric to the collateral 

 type by reduction of the tissue on its inner side, whereby the phloem 

 and the whole of the secondary wood on that side vanished, leaving the 



* Rev. Gen. de Bot. xxsiv. (1902) pp. 420-6. 



t Bot. Gazette, xxxiv. (1902) pp. 216-23 (7 figs, in text). 



