PUBLICATIONS ON AGRICULTURAL BOTANY IN FRANCE. 843 



nitrogen. It seems possible that within a few years we shall know the 

 role of free atuiospheric nitrogen in the nutrition of many of the lower 

 plants. 



L. Mangin,' whose early investigations on respiration are well known, 

 has continued his experiments, studying the eflect of abnormal res- 

 piration. Experiments conducted with plants in an atmosphere 

 containing an excess of carbon dioxid and a deficiency of oxygen 

 showed that respiration and growth were notably checked. This is 

 true of plants whose seeds have an oleaginous reserve rather than 

 of starchy seeds. The same author^ in his studies on the growth of 

 plants in relation to soil aeration has obtained results applicable to 

 tree planting in large towns, namely, that compacted soils are less 

 aerated than those covered with asphalt. Un<1er the intluence of 

 irrigation which renders soil more compact, the quantity of carbon 

 dioxid in the soil atmosphere may increase to IG to 24 per cent. The 

 experiments of Jentys, Bochm, and others have shown that 4 per 

 cent of carbon dioxid in the soil is detrimental to the growth of many 

 plants. The author constructed apparatus for taking samples of the 

 air of the soil and made numerous examinations of it which are 

 reported. He reviews the work of agronomists and hygienists, and 

 discusses the Flemish and Vienna tile drainage systems of aeration 

 and recommends (1) the use of such systems in connection with a 

 system of dee]) drainage and (2) that in case of very tine humus soil 

 stones and gravel be applied in order to increase the permeability of 

 the soil and diminish the evil effects of packing. By this procedure it 

 is thought that the mortality of the trees of parks and promenades, 

 which in Paris annually amounts to 17 per cent for chestnut trees, 2.3 

 per cent for plane trees, 3.G ])er cent for locusts, and for lindens, 

 might be reduced to from 0.5 to 2 per cent. 



W. Palladine ' has continued his work on the correlation between 

 the respiration of plants and their content of nitrogenous substances. 

 For a given temperature and with a sufficient quantity of carbo- 

 hydrates the ratio between the amount of carbon dioxid given off by 

 many plants in an hour and the quantity of undigested nitrogen is 

 constant. Besearch of this nature will be more useful later, when our 

 knowledge of organic synthesis is more advanced. A. Bach/ in his 

 work on the chemical mechanism of the reduction of nitrates and the 

 formation of quaternary nitrogenous compounds, has shown how little 

 we know of this subject. P^rmaldoxime is evidently the first quater- 

 nary compound in the reduction of nitric acid by formic aldehyde, but 

 the ultimate formation of formamid is not demonstrate<l. 



Duclaux'^^ in his investigations on solar action has opened u\) a new 



£ — _ ' _^__-^^_— _^— — — ^-^^^— 



' Corapt. Rend., 122 (1896), ]). 747. 

 2Aiiii.Sci. Agroii., ser. 2, anii.2, 1 (189(>>, ]>. 1. 

 3 Rev. gf'n. I?ot., 8 (1806), p. 225. 

 ^Compt. RciKl., 122 (1806), p. 1190. 

 f Ann. Inst, rastonr, 10 (1806), p. 129. 



