DR. DENNY ON RELATIVE INFLUENCE OF Px\ RENTAGE. 17 
in the production of their progeny, it would assist us immensely in 
carrying out our designs for the improvement in the form and 
colour of our flowers, and the quality of our fruits and vegetables. 
If, for instance, we knew that either parent was prepotent in con- 
veying to the offspring certain qualities, say, of flavour and aroma, 
or of size and form, as regards our fruits, or of colour, perfume, 
form, or substance in our flowers, we should be able to form som.e 
approximate idea of the result that would follow our fertilisations. 
A knowledge too of the ancestry of the varieties we purpose em- 
ploying would also be desirable, to enable us to make allowances 
for the modifications likely to ensue from the tendency to reversion 
towards an ancestral type — a propensity which seems to be inherent 
in all plants that have been much changed from their original state 
by artificial breeding. 
It would also be a matter of scientific interest, as well as 
perhaps of practical importance, to know if the proportionate in- 
fluence borne by the respective parents in crossing varieties is the 
same as in crossing species ? 
As the admission of fecundation is no test of the plants 
employed belonging to the same species, have we any well-defined 
line of demarcation or practical test by which we can distinguish 
between species and varieties, sd that we may know when to employ 
correctly the term hybridisation, and when cross-breeding ? 
Does there exist any real difference in the powers or quality 
of the pollen of the long and short stamens from which we may 
expect to derive any specific effect on the progeny by the exclusive 
employment of the one or the other, or to succeed more readily in 
effecting difiicult crosses ? 
Do certain states of the atmosphere, and if so what apparent 
conditions of it, favour fecundation ? 
Can any clue be obtained, or suggestions offered, to account for 
the antipathies that are found to exist between apparent varieties, 
as well as affinities between what are considered by botanists to be 
distinct species, precluding fertilisation in the former and rendering 
it easy in the latter ? 
These are a few of the most important points that are constantly 
occurring to the practical horticulturist. To how many of them 
does our knowledge admit of a satisfactory reply being given ? 
Prom early youth I have taken much interest in artificial fer- 
tilisation, but have kept no register of my crosses or their results, 
until the controversy arose respecting the tricoloured Pelargoniums, 
as to whether their leaf-markings could be reproduced by fertilisation 
VOL. IV. c 
