540 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Structure of the Petiolar Glands of Hevea brasiliensis.* — 

 A. Daguillon and H. Coupin describe the anatomy of the glands, 

 several of which occur on the upper face of the petiole between the 

 bases of the three leaflets. Each gland consists of a central depression 

 surrounded by a raised ring of tissue ; the epidermis in the depression 

 forms a secretive epithelium with palisade-like cells. Beneath the well 

 developed sub-epidermal layer is a mass of relatively small cells, with 

 dense protoplasm, large nucleus and numerous chloroleucites ; near 

 these are many cells containing crystals of calcium oxalate. Below the 

 periglandular ring is a water-bearing ring of tracheids. A slender 

 woody bundle ends in a cap of small tracheids beneath the centre of 

 the subglandular mass, in which also are found the ends of some lati- 

 ciferous cells. Cells rich in tannin occur in the parenchyma near the 

 secreting surface, and especially in the subglandular mass. 



These petiolar glands afford useful diagnostic characters in several 

 other genera of Euphorbiaceas. 



Vegetative Propagation in the Floral Region in Epidendrum 

 elongatum.t — E. Hemmendorff describes in specimens of this orchid 

 from San Paulo, Brazil, the production of vegetative shoots on the 

 inflorescence. Only a few flowers form fruit ; generally they soon fall 

 and the upper part of the inflorescence withers, but from the axils of 

 the bracts immediately below the floral region new shoots are often pro- 

 duced. These develop in various ways. Only rarely do they bear 

 flowers ; generally they are vegetative, forming naked branches without 

 leaves or roots, or bearing the air-roots, or air-roots and leaves. Occa- 

 sionally shoots of the third order, which are flower-bearing, are developed. 



Gatin, C. L. — Sur les etats jeunes de quelques Palmiers. (On the young states of 

 some palms.) 



[Gives a few details especially in relation lo the root ; in some species only 

 adventitious roots occur. The author states that the three modes of germi- 

 nation of palms distinguished by Micheels represent only superficial 

 differences.] Comptes liendus, cxxxviii. (1904) pp. 1625-7. 



Reproductive. 



Variation in the Violet Flower.^ — 0. E. Britton summarises the 

 variations detected among 1000 flowers of each of five species gathered 

 in various parts of Surrey. The species were Viola odorata, V. hirta, 

 V. silvestris, V. Riviana, V. ericetorum. The most general forms of 

 variation were those tending towards the production of a regular flower, 

 either by an increase in the number of spurs or the formation of petal- 

 line sacs, or by abortion of the typical spur. Petalody of the sepals and 

 stamens, sepalody of the petals, lobing of sepals and petals, and the 

 development of tetramerous and trimerous flowers were also observed. 

 External conditions, chiefly light and temperature, seem to have con- 

 siderable influence on the production of aberrations among violet flowers. 

 The effect of an unusual excess of light was seen in the case of V. silves- 

 tris growing in a copse which had been cut over during the previous 



* Kev. Gen. Botan., xvi. (1904) pp. 82-90 (3 figs, in text).i 



t Arkiv for Botanik (K. Svensk. Akad.) i. (1904) pp. 516-19 (2 pis.). 



X Journ. of Bot., xlii. (1904) pp. 140-8. 



