78 SUMMARY OF CURRENT RESEARCHES RELATING TO 



(4) Structure of Organs. 



Anatomy of Dicotyledons.* — Herr H. Solereder Las collected an 

 immense mass of details respecting the anatomy of the stem and leaves 

 in the various families of Dicotyledons, with a view to their systematic 

 classification on these grounds. A synopsis is given of the chief 

 anatomical characters of each family ; and an account is then given 

 in detail of the structure of the leaf and of the stem. Each section is 

 accompanied by a complete bibliography. 



Flowers of Alsinese.f — A. 0. Wester has investigated the morpho- 

 logy and anatomy of the flowers of this tribe of Caryophyllacese. In 

 Arenaria and Alsine the episepalous stamens form the outer, the epi- 

 petalous stamens the inner whorl ; while in Spergida and Spergularia 

 the reverse is the case ; in Stellaria and Malachium the case is doubtful. 

 The central cylinder divides into two parts, one of which branches into 

 the calyx, corolla, and stamens ; while the bundles which proceed to 

 the wall of the ovary and to the placenta have no connection with one 

 another. 



Floral Scales of Cuscuta.^: — Alida M. Cunningham proposes a new 

 arrangement of the American species of this genus based on the position 

 of the floral scales. Contrary to the view of previous observers, she 

 has arrived at the conclusion that the scales are not epistaminal, and 

 do not form a staminal crown, but are petaloid in their origin, being of 

 the nature of a duplication of the petals. 



Formation of Pollen in Hemerocallis.§ — Mr. E. L. Fullmer thus 

 sums up his observations on the development of the microsporanges and 

 microspores of Hemerocallis fulva. Three or four hypodermal cells of 

 each microsporange become differentiated as the archesporial cells. The 

 wall of the sporange consists of three layers exclusive of the epiderm ; 

 the tapete is a physiological rather than a morphological structure, the 

 peripheral part being organised from the parietal layers, and the axial 

 part from the general tissue. The spindle appears bipolar from its 

 first appearance, being dome-shaped in its early stages ; no trace of 

 multipolar spindles was observed. The spindles often persist for a 

 considerable time after division is complete. Bodies having the appear- 

 ance of centrosomes are frequently seen at the poles. The origin of the 

 supernumerary microspores was not absolutely determined. In many 

 cases, where their origin was indicated by spindles or otherwise, they 

 appeared to arise by the indirect division of one of the tetrad nuclei. 

 r l he pollen-tube nucleus frequently divides by direct division, forming 

 sometimes as many as six or eight nuclei. 



Endosperm Haustoria.|| — Prof. D. M. Mottier describes a special 

 provision in the endosperm of Lilium candidum for increasing the absorb- 

 ing surface in the chalazal region. At the chalaza some of the endo- 

 sperm-cells send out short tubes which penetrate the tissue of the chalaza. 



* ' Systernatische Anatomie d. Dicotyledon*, n,' Stuttgart, 1893, xii. aud 9S4 pp. 

 and 189 figs. See Bot. Gazette, xxviii. (1899) p. 140. 



t Ofv. k. Vetensk. Akad. Forhandl., lvi. (1899) pp. 311-64 (23 figs.) (German 

 abstract). % Pioc. Indiana Acad. Sci., 1898, pp. 212-3. 



§ Bot. Gazette, xxviii. (1899) pp. 81-8 (2 pis.). Cf. this Journal, 1S98, p. 91. 



|| Proc. Indiana Acad. Sci., 1898, pp. 168-9. 



