434 
Derelopmerd of Roots of Agricuitin-al PlanU. 
abounding in starcli-grains. In the common bean, tliiee weeks 
after sowing, tlie cells liave a delicate salmon-tint; but to what 
this is owing I am not able to say, as I have never had time to 
follow out the subject. These bodies are doubtless occasionally 
important organs in time of drought ; though it is very possible, 
as many of them become effete at an early period, they serve 
some especial object besides. The late M. Desmazieres, many 
years since, pointed out to me some curiously-shaped extremely 
minute bodies to which they give rise ; but I am not aware that 
they have been studied in different stages of development, and at 
different periods in the growth of the plant. Something very 
analogous occurs in many conifers ; but in this case, as before, 
further examination is requisite. 
An interesting subject still remains for consideration — namely, 
the activity of absorption in the spongelets at different periods of 
growth. The comparative chemical result of the produce at 
different periods is not a certain indication of this, because this 
may depend upon matter already deposited in the roots, and 
suddenly brought to bear as occasion requires. Unless some 
method could be devised by which the proportion of nutritive 
matter in a given quantity of soil at different peiiods could be 
estimated, it is difficult to see how the matter admits of deter- 
mination. Even comparative estimates as regards the whole plant 
are but few in number, and at present unsatisfactory. It is diffi- 
cult, moreover, to estimate the quantity of active absorbing surface 
at different periods, as old spongelets are constantly decaying. 
It appears, however, from Anderson's Observations on Turnips, 
published in the 'Journal of Agriculture and Transactions- of 
the Highland Society,' that, "in the first half of the time of 
vegetation, the organic labour in the turnip-plant is principally 
directed to the production and development of the external 
•organs ; during a second period of 35 days, 9 parts of the 
food absorbed going to the leaves and 2 parts to the r6ots ; 
while in a third period of 20 days, 9 parts remained in the 
leaves and 16 parts in the roots. During a fourth stage, th(! 
weight of leaves kept constantly decreasing, while that of the 
roots increased, the proportion being much larger than in 
the third stage. 
On chemical examination it appeared that the quantity- of 
phosphoric acid was daily increasing ; the potash increased 
rapidly during the second and third stages, and then decreasetj ^ 
the absorption of sulphuric acid was nearly uniform, while that 
of salt gradually increased and then slightly diminished. As 
regards lime, magnesia, and iron, the absorption showed every 
day a trifling increase, corresponding to the increased absorbing 
surface, but otherwise uniform ; and the same may be said, with 
slight modifications, such as future analysis might alter, of the 
