32 
.lOURNAL OF THE TxOYAL HOETICULTUEAL SOCIETY. 
one unknown quantity : vet the truth of it is often lost sight of in horti- 
cultural work. How often do we hear someone state that, for instance, a 
certain method of planting is superior to all others, but when he is cross- 
questioned on the subject it appears that his belief is merely founded on 
the fact that he has adopted this method and got good results, and if he 
is asked whether in the same season and in the same soil he adopted 
other methods with exactly similar trees, the answer will in nine cases 
out of ten be, No ; and his results, therefore, prove absolutely nothing, 
except that the method adopted is not altogether bad I 
In our own experiments on different methods of treatment, as applied 
to dwarf apple-trees, these are arranged in rows of eighteen, and the 
treatment adopted in each row differs from the normal treatment in one 
particular only : the trees in all the experiments (of which there are 
sixty) were of the same age, and as similar as possible when planted. 
Yet, even when conducted in this way, experiments on trees can by no 
means be regarded as perfect, for it is impossible for any two sets of trees 
to be absolutely comparable. We have in the first place the different 
indi'S'iduality of the trees, to which allusion has already been made, and in 
the second place we have the fact that no two sets of trees can be planted 
in exactly the same place — and the nature of the soil, even in a suitable 
piece of ground, is very far from being uniform throughout. To minimise 
errors due to variation in soil, we have planted at intervals throughout 
the experimental plots seven or eight sets of trees which are not sub- 
jected to any special treatment, and which may, therefore, be termed 
normal ]Dlots. The results from these normal plots, we find, vary a good 
deal in different parts of the ground, but by plotting them out and 
drawing a curve through them we can get a diagram representing 
(probably) the normal results which would be obtained in any part of the 
ground, and this forms a standard of comparison for the results obtained 
in the experimental plots, whatever their position in the ground may be. 
It was, of course, impossible to perform all these sixty experiments 
•with any large number of varieties, as the space required would have 
been too great ; so the bulk of our experiments are contined to three 
varieties only — 'Bramley's Seedling,' ' Cox's Orange Pippin,' and 'Potts' 
Seedling,' all on the paradise stock, six of each in each experiment — but 
these show very characteristic differences in habit, and the results, where 
they agree, should be of a fairly general application. Some of the more 
important experiments are repeated on * Stirling Castle,' as well as on 
standards of ' Bramley,' ' Cox.' and ' Lane's Prince Albert," grown on the 
crab stock. Even in the case of this limited number of varieties it was 
difficult in the first instance to obtain the requisite supply of trees of 
the same age and size. 
These trees are planted at such distances that they may be left till 
they attain maturity without becoming overcrowded, and in applying 
manure to them we have adopted the plan of manuring the ground round 
them to a certain distance only, but increasing this distance every year 
(giving, however, always the same amount of manure per square yard) at 
such a rate that the whole of the ground will be thus manured when the 
trees attain their full growth. The application of artificial manures in 
such a case can bo made in a much more satisfactory manner than if 
