while carefully to study the several treatises published on some of
our old cultivated plants, as on the hyacinth, potato, even the
dahlia, etc.; and it is really surprising to note the endless points
in structure and constitution in which the varieties and sub-varieties
differ slightly from each other. The whole organisation seems to have
become plastic, and tends to depart in some small degree from that of
the parental type.

Any variation which is not inherited is unimportant for us. But the
number and diversity of inheritable deviations of structure, both
those of slight and those of considerable physiological importance, is
endless. Dr. Prosper Lucas's treatise, in two large volumes, is the
fullest and the best on this subject. No breeder doubts how strong is
the tendency to inheritance: like produces like is his fundamental
belief: doubts have been thrown on this principle by theoretical
writers alone. When a deviation appears not unfrequently, and we see
it in the father and child, we cannot tell whether it may not be due
to the same original cause acting on both; but when amongst
individuals, apparently exposed to the same conditions, any very rare
deviation, due to some extraordinary combination of circumstances,
appears in the parent--say, once amongst several million
individuals--and it reappears in the child, the mere doctrine of
chances almost compels us to attribute its reappearance to
inheritance. Every one must have heard of cases of albinism, prickly
skin, hairy bodies, etc., appearing in several members of the same
family. If strange and rare deviations of structure are truly
inherited, less strange and commoner deviations may be freely admitted
to be inheritable. Perhaps the correct way of viewing the whole
subject, would be, to look at the inheritance of every character
whatever as the rule, and non-inheritance as the anomaly.