Meyen’s Report for 1839 on Physiological Botany. 271 
case of ammonia, and hence it is quite comprehensible why 
nitre mixed with the soil in proper quantities is so highly 
advantageous. The idea of the most celebrated chemists, that 
most vegetable substances require only carbon, hydrogen, and 
oxygen to their formation, and that beside these nitrogen is 
only necessary for some certain classes of bodies, is held by 
the author to be erroneous; for he assumes that gluten, legu- 
min, &c. contain lime, phosphoric acid, sulphur, &c., besides 
their usual ultimate constituents, and that these substances 
(gluten, &c.) cannot make their appearance in the plants un- 
less the above-mentioned inorganic bodies are combined with 
them. Sprengel assumes also, that the woody fibres are the 
skeleton of the plant, and consist of Si, Ca, Al, Fe, Mn, C, 
H, O, &c.; the chemists’ idea that the fibres consist of the 
three last-mentioned bodies alone, is in his opinion quite false ; 
for, says he, if one burns the purest possible fibres, there al- 
Ways remains a small residue of ashes consisting of the above- 
mentioned substances. It is a pity that the author has not 
stated more plainly what he means by “ fibres ;” vegetable 
anatomy teaches us the infinitely great variety in the physical 
properties of the membranes which form the cells, and he who 
has attentively followed with the microscope the formation of 
the deposits of new membranes, will plainly see that all those 
inorganic matters, or a great part of them, which are con- 
tained in solution in the sap, out of which the formation of 
the membranes proceeds, must exist either in the substance 
of the hardened membrane or in fine layers between the strata. 
Here, probably, are all the inorganic substances which acci- 
dentally enter into the sap, in larger or smaller quantity. The 
small quantity of ashes found in starch can only be explained 
in this manner. Perhaps, therefore, the author is in error 
when he compares the appearance of the above-mentioned 
matters in the cellular membrane of plants, with the deposi- 
tion of phosphate of lime in the bones of animals, and I have 
already (in the former Reports) drawn attention to the insur- 
mountable difficulties in the way of the experiment, or of a per- 
fect purification of the cells. 
The author considers dung, it is true, as the universal ma- 
nure, but says, that sometimes even this is not sufficient, be- 
cause it contains too little mineral matter. According to his 
ideas, therefore, the plants in such cases were in want of the 
true mineral manures, while, as is well known, this phe- 
nomenon is explained by others in a totally different 
manner. 
The author also states very positively that the soil can then 
only produce good crops, when it is provided with the neces- 
