600 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Connection of the outer and inner Leptome in the Solanacese.* — 

 Herr M. Tswett contests the statement made by some previous observers 

 that, in the stem of the Solanaceae, the outer and inner (extra-xylar and 

 intra-xylar) leptome are not connected with one another, the latter ap- 

 pearing quite independently in the pith of the young hypocotyl. He 

 finds, on the contrary, that, in the genera examined (Datura, Atropa, 

 Solarium, Nicotiana), the two leptomes are always connected with one 

 another by transverse anastomoses. 



Irregular Endoderm in Ruscus.'j' — Mr. T. J. Lewis finds, in the roots 

 of a Ruscus sp., that the vascular cylinder is entirely enclosed by the 

 endoderm, except that in one place a cell of the endoderm was joined by 

 its uncuticularised tangential wall to a complete ring of endoderm exter- 

 nal to the central cylinder. No vascular tissue was contained within 

 this ring, the elements consisting entirely of crushed parenchyme. 

 Further out in the cortex, on the opposite side of the root, was another 

 small isolated ring of endoderm, also enclosing crushed parenchyme. 



Anatomy of the Stem of the Dammar-tree4 — Dr. W. Figdor gives 

 a detailed description of the anatomy of the source of dammar resin, 

 a tree belonging to the Dipterocarpeae, probably a Shorea sp. The 

 resin-passages are found in the perimedullaryjj zone of the stem, but a 

 short distance from the xylem, and are probably of schizo-lysigenous 

 origin. The secreting cells have thick yellowish strongly refringent 

 walls. The resin-passages result from the coalescence of a number of 

 secreting cells. 



Structure of Bowenia.§ — Mr. W. C. Worsdell finds, in the stem of 

 Bowenia spectabilis, strands of extrafascicular vascular tissue, correspond- 

 ing to a similar structure in Cycas, Macrozamia, and Encephalartos, 

 which support the view that these genera are derived from plauts allied 

 to the Medullosae. 



C4) Structure of Organs. 



Origin of Variegated Varieties.|| — M. E. Laurent concludes, as the 

 result of a series of observations, that variegation is brought about by a 

 substance absorbed from the soil through the root, of the nature of a 

 zymase, which causes modifications in the distribution of the chloro- 

 phyll. 



Female Flower of Coniferse.f — Mr. W. C. Worsdell gives a detailed 

 account of the views that have been entertained by various authorities as 

 to the nature of the female " flower " in the Coniferae, accompanied by a 

 copious bibliography. 



The writer himself adopts the " axillary bud " theory of Velenovsky 

 and CeLikovsky, which is supported by the continuous and gradual 

 transition between the undivided seminiferous scale of the normal con- 

 dition and the first transverse pair of foliar organs of the axillary bud, 

 along with the anterior bud-leaf, as well as by the agreement, in the relative 



* Ber. Deutsch. Bot. Ges., xvii. 1S99 (1900) Gen.- Vers. Heft, pp. 231-5. Cf . 

 this Journal, ante, p. 215. t Ann. of'Bot., xiv. (1900) pp. 157-9 (2 figs.). 



t Oesterr. Bot. Zeitschr., 1. (1900) pp. 74-8. 

 § Ann. of Bot., xiv. (1900) pp. 159-60. 

 lj Bull. Soc. R. Bot. Belgique, xxxix. (1900) pp. 6-9. 

 1 Ann. of Bot., xiv. (1900) pp. 39-82 (7 figs.). 



