ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 97 



Oil-receptacles of Hypericum and Ruta.* — Hen- H. Kieuast 

 considers the term " glaucl " as incorrectly applied to these organs. 

 In Hypericum the receptacles have been determined by several ob- 

 servers to have a schizogenous origin. In older stages of develop- 

 ment the membranes of the secreting cells ofier great resistance to 

 sulphuric acid ; this is due to a formation of cork. The dark dots 

 in the leaves of Hi/pericum are merely aggregations of cells without 

 intercellular sjiaces. They originate from a cell which divides in the 

 same way as the mother-cell of the oil-receptacles. 



The oil-receptacles of Huta are also, like those of Dictamnus, of 

 schizogenous origin, originating from a single cell which at first 

 divides regularly into quadrants ; afterwards irregularly. The epi- 

 dermis takes no part ia their formation. 



Extra-floral Nectaries in Gunnera.f — Sig. J. Danielli describes 

 organs which he regards as of this nature found by Sig. Beccari on 

 the surface of the stem of Gunnera scahm, between the leaf-insertions. 

 They have the apjiearance of round regularly lobcd warts, umbonate 

 in the centre, and with a fleshy point. As they grow older the surface 

 becomes more convex, and the umbo and point almost disappear. 

 They have a smooth small-celled epidermis, their substance being 

 composed of a close parenchyma with a central vascular bundle which 

 branches into the lobes. They are of the nature of emergences ; the 

 whole tissue contains cane- and grape-sugar. 



Morphology of the Calyx4 — M. D. Clos contests the ordinary 

 view that the so-called " calyx-tube " of " monosepalous " calices is 

 the result of cohesion of the sepals. It is rather an expansion of a 

 part intermediate in character between axis and appendicular organs, 

 and ought rather to be called the " caliciferous tube." 



Shimmer of the Petals of Ranunculus.§ — According to Dr. M. 

 Mobius, the oily shimmer of the petals of the yellow species of 

 Banunculus difters from that of any other flowers except some species 

 of Acacia. In E. Ficaria this peculiar appearance extends from the 

 tip of the petals downwards for about two-thirds their length, the 

 lowest third being of a dull yellow colour, and the two parts sharply 

 separated, though not by a straight line. The mesophyll contains but 

 little anthoxanthin in the granular form ; the seat of the peculiar 

 colour is the epidermal cells, where it is caused by a highly refractive 

 yellow oil ; this appearance is greatly assisted by the fact that the 

 layer of cells of the mesophyll immediately beneath the epidermis 

 is densely filled with minute starch-grains. 



CompositionofPollen.il — Dr. A. de Planta has studied the 

 chemical composition of the pollen-grains of the hazel. He states 



* Kieaast, H., ' Ueb. die Entwickelung der Oel-behalter iu den Blattern v. 

 Hypericum u. Euta,' 49 pp. (5 pis.). Elbing, 1885. See Bot. Ztg., xliii. (1885) 

 p. 599. 



t Atti della Soc. Toscana di Sci. Nat., vii. (1885) 1 pi. See Bot. Centralbl., 

 xxiii. (1885) p. 303. 



X Mem. Acad. Sci. Toulouse, vi. (1884) pp. 190-206 (1 pi.). 



§ Bot. Centralbl., xxiii. (1885) pp. 115-9. 



II Landwirthschaftliche Versuchsstationen, 1884, pp. 97-114. See Bull. Soc. 

 But. France, xxxii. (188.5). Kev. Bibl., p. 131. 



Ser. 2.— Vol. VI. H 



