ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 781 



0. Pliysiology.* 

 (1) Reproduction and Germination. 



Flowers and Insects. | — Mr. C. Eobertson describes the mode of 

 fertilization and tlio insect visitors in the following Ainorican plants: — • 

 Delphinium tricorne, Nuphar aclvena, Nymphsea tuberosa, N. odorala, 

 Dicentra Cncullaria, Viola pvbesccns, V. palmata var. cucidlaia, V. striata, 

 V. pedata var. hicalor, V. lanceolata, Glaytonia virginica. Tlxe inversion 

 of the flower of most species of Viola appears to be particnlarly favourable 

 to bees of the genus Osmia, the flowers of V. 2)i^l><^scens, palmata, and 

 striata being specially adapted to them. Tbe bearded violets are 

 sternotribe, while V. pedata, which is mainly visited by long-tongued 

 bees, has become nototribe. 



Dimorphism of Polygonum. J— Mr. T.Meehan finds several American 

 sj^ecies of Polygonum (including the European P. Persicaria, aviculare, 

 and Hydropiper') to b' dimorphic, with larger and smaller flowers. The 

 smaller flowers are perfectly ft)rmed, and are abundantly nectariferous 

 and polliniferous, and aj^parently constructed for self-fertilization, but 

 never produce seed. The larger flowers are apparently adapted for cross- 

 fertilization, and are abundantly fertile, but are never visited by insects. 

 They are, in fact, fertilized in the bud, and are frequently cleistogamous. 



Properties of Hybrids. § — Dr. F. Hildebrand gives details of a long 

 series of experiments on hybridization, chiefly between ditferent species 

 of Cistus, Abutilon, Chamsedorea, and Oxalls. In the case of Cliamacdorea, 

 a genus of palms, he finds the hybrids to be perfectly fertile with ono 

 another, although the original parents belonged to shar[)ly difl:erentiated 

 species. lu Oxalis the hybrid presented a mingling of tlie character of 

 the parents in an immense variety of ways. The hybrids generally 

 exhibited a more luxuriant growth than the pure forms, and blossomed 

 earlier. 



(2) Nutrition and G-rowtli (including: JVEovements of Pluids). 



Influence of " Ringing " on Growth. |j — According to Herr T. Miiller, 

 "ringing" of branches produces a more active growth above, a less 

 active growth below the ring ; this is chiefly displayed in the wood, less 

 in the secondary cortex and periderm. Starch is usually entirely absent 

 from the portion below the ring, and tannin is more abundant above 

 than below, while the reverse is the case with calcium oxalate. 



Obtaining of Nitrogen by Graminese and Leguminosae.lf — Herren 

 H. Hellriegel and 11, Willfarth maintain, as the result of a long series of 

 experiments, an essential difference in the mode in which Crramineas and 

 LeguminosfB obtain their nitrogen. The growth of barley and oats is in 

 direct proportion to the amount of nitrates contained in the soil, and they 



* This subdivision contains (1) Kopioduction and Germination; (2) Nutrition 

 and Gruwth (including Movements of Fluids) ; (3) Irritability ; and (4) Chemical 

 Changes (^iucluding Respiration and Fermentation). 



t 'Hot. Gazette, xiv. (l.SS'J) pp. 120-G, 172-8 (4 figs). 



X Proc. Aead. Nat. Sci. Philad., 1889, pp. 59-61. 



§ Jeiiaiseh. Zeitschr. Naturw., xxiii. (1889) pp. 413-548 (2 pis.). 



II ' Ueb. d. Eiufluss d. Eingelschnittes anf d. Dickenwachstlium u. d. StofFvcr- 

 theilung,' Halle, 1888, 53 pp. See Bot. Centralbl., sxxix. (1889) p. 31. 



^ ' Unters. iib. d. Sticlcstoftnahrung d. Gramineen u. Legnminoten,' Berlin, 1,'-8S, 

 234 pp. and 6 pis. See Bot. Centralbl., xxxix. (1889) p. 138; and Ber. Deutaeh. 

 Bot. Gescll., vii. (1889) pp. 138-43. 



