ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 475 



B. Physiology. * 



Fertilization of Greenland Ericaceae.f — Prof. E. Warming speaks 

 of the biology of the species of EricacesB gathered in Greenland, 

 sixteen in all, especially with reference to the arrangements for polli- 

 nation. All have coloured flowers ; many are scented, and all except 

 Pyrola produce honey. The position of the corolla, and the very 

 common presence of hairs inside, all point to cross-fertilization, 

 although in most cases self-fertilization is quite possible. The pollen- 

 grains are in all cases smooth and dry, and united into tetrads. All 

 the Greenland Ericaceae are more or less shrubby ; and in all, except 

 Vaccviium tdiginosiim, the leaves are deciduous. 



Influence of Oxygen at high Pressure on the Disengagement of 

 Carbonic Anhydride by Germinating Plants.| — The general result 

 of the experiments made by Dr. W. Johannsen with air and oxygen at 

 the ordinary pressure, and at 2, 4, and 5 atmospheres, is that the 

 disengagement of carbonic anhydride increases at first as the pressure 

 of oxygen increases, but that this increase is only temporary; the 

 respiration gradually diminishes (more quickly as the pressure is 

 greater), and the plants rapidly die. The most interesting result of 

 the experiments is the discovery of an inductive eflfect exercised by 

 the presence of oxygen at a high pressure for a short time ; as soon 

 as the ordinary pressure is restored a great increase in the respiration 

 is obtained, amounting to as much as 50 per cent, in the case of maize. 

 The cause of this inductive action is unknown. 



Assimilation and E.espiration.§ — Prof. U. Kreusler has carried 

 out a series of experiments with the view of determining the proportion 

 of carbon dioxide in the atmosphere most favourable to the assimila- 

 tion of plants, and finds that it lies between 1 and 10 per cent. In 

 dry air plants assimilate much less strongly than in air that is mode- 

 rately moist ; hence the comparative suspension of the growth of 

 vegetation during very dry weather. Complete saturation of the 

 atmosphere appears to have in itself no unfavourable influence on 

 transpiration. The efiect of the electric light, as compared with day- 

 light, whether difiiised or direct sunshine, was very greatly to reduce 

 the amount of assimilation in proportion to the respiration. 



Apical growth and Phyllotaxis.|| — Prof. S. Schwendener brings 

 further arguments in favour of his view that there is no coincidence 

 in the mode of apical growth in all the higher plants. It is well 

 established that in the roots of Marattiaceas there are four apical cells. 



* This subdivision contains (_1) Reproduction (including the formation of the 

 Embryo and accompanying processes); (2) Germination ; (3) Nutrition ; (4) Growth; 

 (5) Respiration ; (6) Movement ; and (7) Chemical processes (including Fermen- 

 tation). 



t SB. Botan, Sallsk. Stockholm, April 22, 1885. See Bot. Centralbl., xxv. 

 (1886) p. 30. 



X Untersucb. Bot. Tnstit. Tubingen, 1885, pp. 686-717. Cf. Journ. Chem. 

 Soc. Lond., 1. (1SS6) p. 274. 



§ Verhandl. Naturh. Ver. Preuss. Rheinlande, xlii. (1885) pp. 330-7. 



II SB. K. Preuss. Akad. Wiss., xl. (1885) pp. 921-37 (1 pi.). 



2 I 2 



