138 Dr. Meyen's Researches in Physiological Botany. 



kilogr. In another very productive alternation (?) which was 

 however abandoned on account of the climate, the quantities 

 of matters taken from the atmosphere appeared to be much 

 greater. The produce contained 7600 kilogr. carbon, and 160 

 nitrogen more than the manure employed ; by a three years 3 

 alternation, the fourth year the ground being manured and 

 lying fallow, the quantity of carbon absorbed from the air was 

 only 4358, and of nitrogen 17 kilogr. 



According to M. B/s researches, of all our common culti- 

 vated plants, Helianthus tuberosus takes up most from the at- 

 mosphere, and therefore this is the plant with which the small- 

 est quantity of manure produces the largest quantity of nutri- 

 tious matter. The chemical composition of the several pro- 

 ducts have been placed together in a table : in it we find the 

 ultimate analyses of wheat, rye, barley, wheat-, rye-, and barley- 

 straw, potatoes, beetroot, turnips, Helianthus tuberosus and of 

 its stalks, yellow peas, pea-straw, red sorrel, and of manure. 

 M. Boussingault remarks, that most of these nutritive sub- 

 stances have different tastes, but at the same time almost the 

 same ultimate constitution. It cannot be said that these bo- 

 dies consist of carbon and water, for in almost every instance 

 there was a small excess of hydrogen ; and from this it follows 

 that during vegetation water is decomposed, as MM. Edwards 

 and Colin (Report for 1838, p. 7) are said to have proved. 



A very advantageous report of the above research was given 

 to the Academy on the 14th of January, 1839, in the name of 

 the Commission, by M. Dumas. 



M. Unger, in a treatise, entitled e Die Antritz quelle bei 

 Gratz in Bezug auf ihre Vegetation*,' the contents of which 

 are principally of a physical nature, has made known a num- 

 ber of observations, from which he arrives at the conclusion, 

 that the free carbonic acid in springs has no influence in pro- 

 moting vegetation, that it nevertheless causes the appearance 

 of some plants, and must therefore be ranked among those 

 causes which influence the quality of the vegetation. 



M. Nietner, court-gardener in Schonhausen, near Berlin, 

 has explained his views with regard to the necessity of vary- 

 ing plants, in order to arrive at successful results in their cul- 

 tivation f. The theory, he states, is on the whole as follows : 

 C( The spongioles being the only parts of the subterraneous 

 part of the plant which imbibe nourishment, give off certain 

 substances, which for succeeding plants, if they be of the same 



* Linnaea of 1 839, pp. 339—356. 



f Kurzer Umriss der Rotation oder des Wechsels der Pflanzen. Verhand- 

 lungen des Vereins zur Beforderung des Gavtenbaues in den Preussischen 

 Staaten, xiv. 1839, pp. 158—162. 



