ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 783 



of the cells belonging to the rays — all of which are fulfilled in the wood. 

 Although Dr. Janse's observations were made chiefly on Conifers, he does 

 not think the results would have been essentially different had the wood of 

 Dicotyledons been the subject of investigation. 



(4) Chemical Changes (including Bespiration and Fermentation). 



Supposed Reduction of Nitrates by Barley and Maize. * — -M. A. 



Jorissen gives the results of some experiments which he performed with a 

 view of finding out whether nitrates are reduced by barley or maize. The 

 grains were first placed for half an hour in a dilute solution of mercuric 

 chloride ; they were then washed in boiling water, and afterwards placed 

 in boiling distilled water for twenty-four hours. The author then caused 

 them to germinate in tubes previously sterilized, and when the rootlets 

 were about a centimetre long they were placed in a 1 per cent, solution of 

 potassium nitrate. At the end of twenty-four and forty-eight hours the 

 liquid was examined for nitrous acid. No reduction was found to have 

 taken place. This result is contrary to that obtained by Laurent and 

 Schonbein. The author attributes the reduction which took place in their 

 experiments to the presence of living organisms in the culture liquids. 



Liberation of Nitrogen from its compounds, and acquisition of 

 atmospheric Nitrogen by Plants. t — The conclusions arrived at by Mr. 

 W. 0. Atwater are the following : — (1) During the growth of peas, nitrogen 

 is in most cases acquired from the air ; but in some few cases where the 

 conditions of growth are abnormal, there is either no gain in nitrogen or 

 there is a slight loss. This loss is to be explained by the evolution of free 

 nitrogen from the nutriment, or from the seeds and plants during germination 

 and growth ; it is probably a constant, and may cause considerable error in 

 all the experiments. (2) Boussingault has found the amount of atmospheric 

 nitrogen absorbed to be very small ; but in his experiments the plants were 

 not normally nourished, and probably, therefore, were less able to resist 

 the action of denitrifying ferments or to absorb nitrogen from the air. 

 (3) Numerous experiments have shown a slight gain or loss of nitrogen 

 during germination and growth, but the failure of an experiment to show 

 the acquisition of nitrogen from the air proves the non-assimilation of 

 atmospheric nitrogen only on condition of the further proof that no 

 nitrogen was liberated. (4) The liberation of nitrogen appears to be due 

 in some cases, if not in all, to ferments, (5) The way in which the 

 nitrogen is acquired is still a matter of doubt. (6) The experiments of 

 Boussingault, and of Lawes, Gilbert, and Pugh, which have given the 

 strongest evidence against the fixation of free nitrogen by plants, are 

 possibly affected by the loss of nitrogen already referred to, by the exclu- 

 sion of the action of electricity and of microbes, and by the fact that the 

 plants were also for the most part poorly fed. (7) In the author's experi- 

 ments ignited sea-sand was used for growing the plants in, and hence it is 

 probable that the plants themselves and not the soil are factors in the 

 acquisition of atmospheric nitrogen. (8) Lawes, Gilbert, and Warincton 

 have shown the great probability that leguminous plants, which appear to 

 possess in a high degree the power of obtaining nitrogen from natural 

 sources, induce the action of nitrifying ferments by which the inert nitrogen 

 of the soil is made available. It is equally conceivable that the same plants 

 and others may favour the action of nitrogen-fixing micro-organisms. 



* Bull. Acad. E. Sci. Belg., xiii. (1887) pp. 445-8. 



t Araer. Chem. Journ., viii. (1886) pp. 398-420. See Journ. Cheiu. Soc. Loud., 

 1887— Abstr., p. 515. Cf. this Journal, ante, p. 270. 



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