Dr. Meyen’s Researches in Physiological Botany. 137 
quantities of inorganic matters, and the same result was ob- 
tained on incinerating the chaff, the straw, and the roots ; and 
it moreover appeared that the roots and chaff were the richest 
in inorganic substances. The entire plants contained by 
weight from 3°7 to 4°08 per cent. The quantitative exami- 
nation of the ashes showed that the quantities of silicic acid, 
lime, magnesia and alumina were nearly the same in the plants 
grown on all the different soils. 
The conclusions which M. Lampadius has drawn from these 
analyses appear certainly quite evident; but at the same time 
I may be allowed to remark, that the results would have 
turned out quite differently ifhe had chosen some more easily 
soluble salts as manure, instead of chalk, silicic acid, &c., and 
that the above experiments would have been much more va- 
luable if he had before given the analysis of the soil with the 
‘manure used; and therefore I believe that the question as to 
whether the roots are able to select this or that substance, re- 
mains completely unanswered by this in other respects highly 
interesting research. 
M. Boussingault has continued his chemical researches on 
vegetation*, and has this time chosen as his subject the im- 
poverishment of the soil and the study of the benefits of “ alter- 
nation (wechselwirthschaft—assolemenst).” In the researches 
of M. Boussingault alluded to in last year’s Report, it was 
shown that plants receive a part of their nourishment from 
the air; and in the present memoir M. B. endeavours to 
show that the most fruitful “ alternation” (!) is that by which 
the greatest quantity of elementary bodies is absorbed from 
the atmosphere. Now it is highly important to know the 
exact quantities derived from the-air, in order to be able to 
compare the merits of different methods of cultivation. On 
an estate, with the products of which M. B. was well ac- 
quainted, it was found, that the manure which was used for 
one hectare of land contained 2793 kilogrammes carbon. The 
produce from this piece of land contained on the other hand 
8383 kilogr. carbon, and from this M. B. concludes, that the car- 
bon derived by the plants from the air was at least 5400 kilogr. 
The given quantity of manure for one hectare of land contained 
157 kilogr. nitrogen, while the produce contained 251, and 
therefore the atmosphere must have yielded the excess of 94 
* «Te la discussion de la valeur rélative des assolemens par l’analyse élé- 
mentaire.”—Ann. des Sciences Naturelles, Part. Botan. 1839, t. xi. pp. 31— 
—38.” 
+ Wechselwirthschaft. Different kinds of corn or other plants are culti- 
vated on a piece of ground in a certain succession for three or more years; the 
land is then allowed to lie fallow for a certain time, and then the same suc- 
cession or alternation is proceeded with. 
