7.41 | 6.53 | 9.01 | 6.66|
| Lower part | | | | | | |
| of straw | 5.33 | 5.18 | 9.76 | 7.11 | 7.30 | 6.93|
+-------------+-----------+---------+-----------+-------+-------+------+

The specimens of oats on which these analyses were made were from
different districts of country, grown on soils of different quality, and
were, further, of different varieties; and yet they show, on the whole,
a remarkable similarity in the proportion of ash in each part, and
indicate that there is a normal quantity belonging to it. Such a series
of analyses also affords the most convincing proof that the inorganic
matters cannot be fortuitous, and merely absorbed from the soil along
with their organic food, as the old chemists supposed, because, in that
case, they ought to be uniformly distributed throughout the entire
plant, and not accumulated in particular proportions in each individual
organ.

Not only does the proportion of ash vary in the different parts of a
plant, but even in the same part it is greatly influenced by its period
of growth. The laws which regulate these variations are very imperfectly
known, but in general it is observed that during the period of active
growth the quantity of ash is largest. Thus, it has been found that in
early spring the wood of the young shoots of the horse-chesnut contains
9.9 per cent of ash. In autumn this has diminished to 3.4, and the last
year's twigs contain only 1.1 per cent, while in the old wood the
quantity does not exceed 0.5. Saussure has also observed that the
quantity of ash diminishes in certain plants when the seed has ripened.
Thus, he found that the percentages of ash, before flowering, and after
seeding, were as follows:--

Before flowering. With ripe seed.
Sunflower 14.7 9.3
Wheat 7.9 3.3
Maize 12.2 4.6

On the other hand, the quantity of ash in the leaves of trees increases
considerably in autumn, as shown by this table:--

PER-CENTAGE OF ASH IN
May. September.
Oak leaves 5.3 5.5
Poplar 6.6 9.3
Hazel 6.1 7.0
Horse-chesnut 7.2 8.6

In general, the proportion of ash appears to increase as the plant
reaches maturity, and this is particularly seen in t