916 SUMMARY OF CURRENT RESEARCHES RELATINa TO 



the drying up of the pools or ditches in the spring ; the conditions 

 then become those of terrestrial growth ; the stem becomes erect, and 

 is thickly clothed with bright green leaves, divided into many short, 

 somewhat stiff, filamentous points, constituting a variety B. aquatile 

 var. succulentum (the B. siicculentum of systematists, the Banunculus 

 pantothrix of De CandoUe). Besides these variations in the form of 

 the leaves, this plant is also subject to variations in their texture. 

 Thus, in some cases, when removed from the water, the immersed 

 leaves collapse and fall together like the hairs of a wet brush, while 

 in others their rigidity causes them to remain distinct ; this circum- 

 stance is due to differences in the development of the fibro-vascular 

 bundles in the two cases. The varieties thus formed may be termed 

 laxa and rigida, respectively. Variations in the flowers are also 

 brought forward by the author, constituting the varieties macranthum 

 and micrantlmm, but their connection with external conditions is not 

 shown. But allowing these, as well as the variations indicated by the 

 terms rigida and laxa, to occur in the case of each of the above-men- 

 tioned varieties and sub-varieties, the total number of actually occur- 

 ring permutations and combinations of these different states of 

 variation is set down as twenty-two in the single species B. aquatile ; 

 and the author declares that more might still be added from fresh 

 water, while the brackish-water forms have not been even mentioned. 

 He finds in this extraordinary variability the best possible arguments 

 against the doctrine of constancy of species. A larger and more 

 detailed work on the subject is promised. 



Respiration of Plants.* — M. Borodin maintains, as the result of 

 a fresh series of observations, that the energy of respiration of a leafy 

 shoot is, under equal external conditions, a function of the amount of 

 carbohydrates present in the plant. In confirmation of this view, he 

 adduces the fact that red light and a greater intensity of light have a 

 more powerful effect than blue or a less intense light. Direct exjieriments 

 showed that when a plant was exposed for a long period to an atmo- 

 sphere rich in carbonic acid (at least when the proportions did not 

 exceed 7 per cent.), in the dark, no acceleration of the respiration 

 resulted, such as always takes place in the ordinary air under the 

 influence of light. Eespiration does not, therefore, depend on the 

 carbonic acid as such, but on its decomposition in the light. 



Further experiments were made by the author on the absorption of 

 carbonic acid by air-dried parts of plants, especially seeds. He found 

 absorption to take place to a considerable extent, the carbonic acid 

 being again given off into air, which contained but little of that gas. 

 This absorption took place in the case of seeds rich in starch or oil. 

 Air-dried seeds were found not to respire. Among other gases, the 

 absorption of hydrogen by air-dried seeds was determined, but in 

 inconsiderable quantities. 



Colours of Spring Flowers. — Mr. A. W. Bennett, in a paper read 

 at the York meeting of the British Association, suggests an explana- 



* Mem. Acad. Imp. Sci. St. Pe'tersbourg, xxviii. (1881) 54 pp. (2 pis.). 



