208 
THE REJECTION OF PLANTS. 
tubers, and we imagine that the advantages which these derive from an occasional 
removal from the soil, are not only attributable to what is usually termed " a 
season of rest," but also to a change of soil ; hence, the good effects of such treat- 
ment will be greatly diminished, if this latter fact is not taken into consideration 
and acted upon. 
Plants in pots are still more materially affected by their own rejections, on 
account of their roots being more confined, and consequently unable to extend 
themselves into uncontaminated soil; but even in this case there are means of 
removing them, or counteracting their effects, which we shall now explain. It 
has been asserted, but we scarcely think it has been sufficiently demonstrated, that 
this excrementitious matter is voided solely by the tips or extremities of the 
rootlets ; and if this be correct, the importance of their being repotted annually 
must be very evident. These rootlets, it is well known, are usually found at the 
sides of the pots, and by removing a portion of the external soil of the ball, this 
injurious matter will be entirely taken away, and fresh soil may be substituted in 
its place. The fibrous roots of many plants likewise lie near the surface of the 
soil, and with such plants the operation called " top-dressing " has a beneficial 
effect, similar to that of potting with others, provided always a portion of the 
surface-soil be taken away before any fresh earth is added. 
But there are other means of removing or neutralising these rejections, a know- 
ledge of which is equally essential to the gardener or cultivator of plants ; and 
these are, a free circulation of water, and a thorough exposure to the air. By the 
advantage resulting from the former of these processes, it will be seen that an 
efficient drainage to plants in pots is necessary for other purposes than are usually 
considered ; and that a stagnation of water about the roots, besides saturating the 
plants, and thus, as we conceive, making their rejections more abundant, causes a 
retention of this noxious feculence in the pots, which is highly pernicious and 
sometimes destructive to the plants. 
By freely exposing soil to the varied influences of the atmosphere, it has been 
proved that the rejections of plants which it contains are either evaporated or 
decomposed. Hence the great advantage of spreading out soils to the air, and 
frequently turning them previously to using them for potting. Perhaps also this 
may be one instance of the utility of the operation of digging, and a still more 
prominent one in that of ridging. It is certain, however, that the practice of 
throwing away expensive and valuable soils after they have once been used for 
potting plants, is a most injudicious and wasteful proceeding ; since, by exposing 
them to the air for one or more years, and repeatedly turning them, they might 
again be rendered available for the same purpose ; and with a slight addition of 
well-rotted manure to enrich them, would be equally suitable and nutritive to the 
same or any other similar kind of plants. We would especially direct the attention 
of those of our readers who have to purchase soils to this latter declaration ; and to 
establish the truth of it, we need only say, that were this theory not correct, every 
