212 THE JOURNAL OF INDIAN BOTANY.
Senecio Lawsoni Gamble sp. nov. 1. c. p. 342, allied to S. lavandulacfolius
DC, but with small leaves uniformly borne by the etem, few flowered
corymbs and many nerved ligules, Dist. Nilgiris : Avalanche to Sisparah.
Physiology
Beckley, V. A The preparation and fractionation of Humic acid ; and the formation of Humus. Jour. Agric. Science, XI, 1st January, 1921, pp. 66 & 69.
In the first of these papers the author describes experiments which go to show that humic acid obtained by ashing the humus obtained from an alkaline extract of soil by an acid or by boiling sugar with acid is a mixture of two acids, separable by pyridine ; one probably tri-basic and the other terra-basic ; and not one body as previously supposed.
In the second he shows that carbohydrates when acted on by acids, whether mineral or amino, produce hydroxymethyl-furfural, (a ring com- pound consisting of an oxygen atom linked to 4 carbons, to which are attached CH2 OH ; CH ; and CHO respectively) and that this condenses to humus. This is the process whether the action takes place in the laboratory or the held, and whether from sugar, celluluse or straw. No evidence could be obtained that hydroxymethyl-furfural was produced during the decomposition of cellulose by Spirochseta cytophaga.
P. F. F.
Harrison, W. H. Carbon dioxide in relation to rice soils. Memoirs of the Department of Agriculture in India. Chemical Series V. 8th November, 1920.
In a previous paper the author and Subramanya Aiyar showed that the gasses of paddy soil are mainly methane and nitrogen, while carbon-dioxide and hydrogen occur only in small quantities. But in ordinary decomposi- tion of organic matter under anerobic conditions, such as presumably obtain in paddy soil, the opposite is the case, there is little nitrogen and much hydrogen and carbon-dioxide. From the experiments described in this paper the author concludes that this difference is due not to the fermentation being of a different type, but to secondary chemical changes where by the hydrogen and carbon-dioxide produced combine to form organic matter and methane. The result of this is that there is less hydrogen available to absorbe oxygen, thus increasing the amount of the latter available for eeration of the roots. Another advantage to the plant is the removal of the carbon-dioxide. The methane is also of use since it increases the oxygen supply by the action of the surface film, as shown in a previous paper. The organic matter so formed will also be decomposed in like manner, with fresh evolution of methane and nitrogen. In this way com- paratively large quantities of nitrogen are set free, and there is no need to postulate the action of specific bacteria,
P. F. F.
