Hence if man goes on selecting, and thus augmenting, any peculiarity, he will almost certainly modify unintentionally other parts of the structure, owing to the mysterious laws of correlation.

The results of the various, unknown, or but dimly understood laws of variation are infinitely complex and diversified.

It is well worth while carefully to study the several treatises 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 of structure and constitution in which the varieties and sub-varieties differ slightly from each other.

The whole organisation seems to have become plastic, and departs in a slight degree from that of the parental type.