finally when fully or almost fully grown. But in some cases, which are
always specified, owing to the want of time, only one or two of the
tallest plants on each side were measured. This plan, which is not a
good one, was never followed (except with the crowded plants raised from
the seeds remaining after the pairs had been planted) unless the tallest
plants on each side seemed fairly to represent the average difference
between those on both sides. It has, however, some great advantages, as
sickly or accidentally injured plants, or the offspring of ill-ripened
seeds, are thus eliminated. When the tallest plants alone on each side
were measured, their average height of course exceeds that of all the
plants on the same side taken together. But in the case of the much
crowded plants raised from the remaining seeds, the average height of
the tallest plants was less than that of the plants in pairs, owing to
the unfavourable conditions to which they were subjected from being
greatly crowded. For our purpose, however, of the comparison of the
crossed and self-fertilised plants, their absolute height signifies
little.

As the plants were measured by an ordinary English standard divided into
inches and eighths of an inch, I have not thought it worth while to
change the fractions into decimals. The average or mean heights were
calculated in the ordinary rough method by adding up the measurements of
all, and dividing the product by the number of plants measured; the
result being here given in inches and decimals. As the different species
grow to various heights, I have always for the sake of easy comparison
given in addition the average height of the crossed plants of each
species taken as 100, and have calculated the average height of the
self-fertilised plant in relation to this standard. With respect to the
crowded plants raised from the seeds remaining after the pairs had been
planted, and of which only some of the tallest on each side were