472 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Dr. Beccari explains tlie phenomenon on the basis of variability 

 and heredity. When a seed of Myrmecodia falls on the branch of a 

 tree and germinates, a small swelling makes its appearance on the 

 tigellum, serving the purpose of a reservoir of water for the plant 

 during the dry season, but never attaining any great development 

 without the intervention of ants. When these visit it for the sake of 

 food, they cause a hypertrophy of the cellular tissue similar to that of 

 galls ; and this individual peculiarity is transmitted to the descendants 

 until it becomes fixed by heredity. These phenomena occur in many 

 species of Myrmecodia and Sydnophyium. 



Dimorphism of Jasminum.* — Sig. E. Pirotta describes a species 

 of Jasminum, J. revolutum Sims, with short-styled and long-styled 

 flowers, accompanied by the ordinary differences in the position of the 

 stamens and the size of the pollen-grains. Both forms are proter- 

 androus. 



Causes of the Zygomorphy of Flowers.! — Dr. H. Vochting dis- 

 tinguishes between two kinds of zygomorphy, constitutional, when 

 the flower itself developes a monosymmetrical form, e. g. Aconitum ; 

 and accidental, when the original polysymmetrical form of the 

 flower becomes monosymmetrical by the movements of particular parts. 

 This last kind of zygomorphy, of which Epilobium angustifolium is 

 a good example, is entirely the result of geotropism, which causes the 

 sepals and petals to bend upwards, the stamens and styles to bend 

 downwards. 



Bud-Scales of Conifers.f — As the result of an examination of sixty- 

 three species, Herr J. Griiss states that in by far the greater number of 

 conifers the young shoots are covered by bud-scales furnished with a 

 very resistent epidermis on their under side, usually composed of elon- 

 gated sclerenchymatous cells, the outermost wall of which is much 

 thicker than the rest, and distinctly laminated ; they usually possess 

 pores and a delicate cuticle ; the cell-cavity is small, and sometimes 

 entirely closed. This typical form occurs in Picea, Abies, Tsuga, 

 Pinus, Cedrus, Larix, and Torreya, 



A considerable number of conifers {Gephalotaxus,Podocarpus, &c.), 

 have buds with a simple epidermis. In Araucaria Bidwillii and 

 Cunninghamia sinensis there are no buds, the period of growth begin- 

 ning with the development of scale-like leaves, which exhibit the 

 structure of ordinary leaves only to a rudimentary extent. These 

 species present a transition to those like the Cupressinea?, which pro- 

 duce no bud-scales. 



In many cases the development of bud-scales is clearly related to 

 the habit and climate of the species. 



Mechanism for the Opening* of Pore-capsules§ — According to 

 Dr. G. Beck the bursting of pore-capsules is always due to the drying 



* Rend. R. Istit. Lombardo, xviii. (1885) 5 pp. See Bot. Centralbl., xxv. 

 (1886) p. 201. 



t Ber. Deutsch. Bot. Gesell., iii. (1885) pp. 341-5. 



X Griiss, J., ' Die Knospenschuppen der Coniferen,' 43 pp. and 1 pi., Berlin, 

 1885. See Bot. Centralbl., xxv. (1886) p. 38. 



§ Verhaudl. K. K. Zool.-Bot. Gesell. Wien, xxxv. (1886) pp. 23-4. 



