ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 531 



spaces and epidermal cells were smaller, and the latter had somewhat 

 wavy outlines. In Nuphar pumilum the leaves were smaller and 

 contained less starch. 



The author concludes that the incapacity of certain water plants 

 to produce branches outside the water depends on their inability to 

 resist strong transpiration, and not on any incapacity to grow and 

 nourish themselves in the air. They thrive in the air if it is only 

 sufficiently moist to reduce transpiration to a small amount. 



Insectivorous Plants.* — A. F. W. Schimper gives detailed descrip- 

 tions of several insectivorous plants, natives of North America. 

 In the first place, the structure is more fully described than hereto- 

 fore of the ascidiform leaves of Sarracenia purpurea. It was clearly 

 determined that the products of decomposition of the insects and 

 other organic substances found in the pitchers enter the cells of the 

 leaf, as is shown by the changes which take place in the protoplasm 

 of the cells thus affected. In these cells Schimper noticed a pheno- 

 menon closely resembling that described by Darwin as occurring in 

 Drosera under the name " aggregation of protoplasm." In fact, how- 

 ever, in Sarracenia, the aggregations consist of a concentrated 

 solution of tannin, which substance is always present in the cell-sap. 



There occur in North America three species of JJtricularia, land- 

 plants growing in moist sandy situations. Of these U. cornuta was 

 especially examined, and presents several very singular points of 

 structure. The plant possesses no true root, the rhizome branching 

 into several root-like organs, which bear the bladders in great 

 quantities, and which the author believes to be homologous to the 

 floating leaves of the aquatic species. The bladders are similar in 

 form to those of TJ. vulgaris, but want the " antennas," as is also 

 their histological structure, which is described in detail. They con- 

 tain, besides inorganic bodies, small animals and Algae, especially 

 diatoms, rotifers, and Crustacea ; the animals were never found alive, 

 but usually much swollen and decomposed, and this was also the 

 case with the diatoms, the contents of the bladders being apparently 

 poisonous to both animals and plants. The hairs of the bladders 

 appear to act as organs of absorption; and in the contents of tLeir 

 cells similar changes were observed to those described in the cases 

 of Sarracenia and Drosera. As in Dionaia, an excess of nutriment is 

 injurious to the plant. 



Climbing Plants.f — In opposition to the view of Von Mohl, 

 S. Schwendener denies the existence of a special faculty of irrita- 

 bility to which the twining of climbing stems and tendrils is due. 

 He considers all the phenomena of these organs to be explicable by 

 the laws of circumnutation and of geotropism. 



Power of Movement in Plants.f — In J- Wiesner's work on this 

 subject he goes through the results published by Darwin in his work 



* Bot. Ztg., xl. (1882) pp. 225-34, 241-8 (1 pi.). 



t SB. Bot. Ver. Prov. Brandenburg, xxiii. (1882) pp. 9-11. 



% Wiesner, J., ' Das Bewegungsvermogen der Pflanzen,' 212 pp., Vienna, 1881. 

 See Bot. Ztg., xl. (1882) pp. 202-8. See also ' Nature,' xxv. (1882) pp. 578-82; 

 597-601. 



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