7 6 
V. //. Blackman. 
Dealing first with the simplest cases in which the parent races 
differ in one character, such as the form of the seed or the colour of 
the cotyledon, it was found that in the second generation (the original 
hybrids themselves being considered the first generation) individuals 
appeared with the recessive character only, and these were always 
almost exactly one quarter of the whole number of the second gene¬ 
ration ; in other words, the hybrids exhibiting the dominant character 
gave rise to plants which had either the dominant or the recessive 
character, and these always in the proportion of 3 to 1 . Mendel 
found that this ratio held for all the characters investigated and no 
transitional forms were observed Plants with the recessive and 
plants with the dominant character were often produced from one 
and the same hybrid. The variations were very great in different 
individuals, thus one plant would produce seeds which were nearly 
all yellow in the cotyledon while another would produce seeds with 
yellow and seeds with green cotyledons in about equal numbers; 
when, however, a large number of plants were considered the 
relative number of dominant and recessive forms in the second 
generation was always very close to the ratio of 3 to 1 . 
Continuing the study further it was found that the forms 
which exhibited the recessive character in the second generation 
were pure' 1 ' forms, for they produced offspring in the third generation 
with the recessive character only, thus one quarter of the forms of 
the second generation are pure recessive forms. Of the forms 
with dominant characters (which represent three-fourths of the 
second generation) one-third are obviously pure forms, for in the 
third generation they produce offspring with only the dominant 
character; the other two-thirds are obviously of hybrid nature, for 
though themselves exhibiting only the dominant character, they 
produce offspring with both dominant and recessive characters and 
that in the same proportion as in the second generation, namely, 
3 to 1 . It is thus clearly shown by a study of the third generation 
that the original hybrids by self fertilisation produce offspring 
(the second generation) of which one quarter are pure forms with 
the recessive character, one quarter pure forms with the dominant 
character, and only one half hybrid forms which are shown to be of 
*Those forms which both in themselves and their offspring 
exhibit a character or characters derived from one original 
parent only are considered “pure” forms, since they no longer 
show that they are of mixed origin. Similarly those forms 
which, in themselves or their offspring exhibit characters 
derived from both original parents must still retain their mixed 
nature, and so are considered as hybrids. 
