ABSTRACT
From the outset Gregor Johann Mendel had a clearer understanding of his task than had any of his predecessors. Mendel’s experiments in hybridisation broke trail in three different ways. Whereas his predecessors had hybridised species or varieties which differed from one another more or less in very numerous qualities, he hybridised forms of the same species which differed from one another only in respect of one or a few characters. From various sources, Mendel got together thirty-four different kinds of pea, tested the strains as to purity for two years, and then selected twenty-two of them as suitable for his experiments. Most of these varieties were considered by him to belong to the species Pisum sativum; the others, he held, were Pisum quadratum, P. saccharatum, and P. umbellatum. Taking two vigorous plants which differed in respect of one of the before-mentioned pairs of characters, Mendel crossed them mutually, pollinating the first from the second and the second from the first.
