28 
FOURTEENTH REPORT. 
form, and color of our twentieth century sweet peas was produced. 
Our sweet peas are the result of promiscuous hybridizing and con- 
tinuous selection, but crossing for definite ends has often been practiced 
with success. As for instance, when the hardy Citrus trifoliata, of 
Japan is crossed with the orange of commerce thus producing the 
“eitranjre.” This fruit is not as large as the 
orange 
but of 
excellent quality and can probably be improved by selection. As these 
plants will endure 20° of frost the range of orange culture will be 
extended northward several hundred miles. 
We cannot stop longer to consider hybridization though it has been 
productive of our most useful and beautiful plants. We have already 
noticed the unexpectedness of its results. Its eccentricities seemed end- 
It was lawless. But with the opening of this century all has 
been changed. A law — for such I believe it may properly be called— 
was made known that promises to bring order out of chaos and in time 
furnish methods to the breeder, of quite unprecedented importance. 
Need I repeat the oft told tale, one of the tragedies of science? How 
for thirty live years the published results of the work of August Mendel 
remained unappreciated and forgotten and it was not till long after the 
death of the unknown abbot of Briinn that his great discovery startled 
the biologic world. 
Nor need I repeat to this audience the nature of Mendel's experi- 
ments nor the important generalizations to which they lead. He it was 
who first applied careful experimentation to problems of heredity and 
the results achieved and wide-reaching theories founded on them have 
been confirmed and extended by many followers in the past decade. 
Mendel’s law became known in 1900. The method of experiment as 
applied to problems of genetics was soon to bear further fruit. The 
following year the “Mutation Theory” was published, tin 1 next great step 
in making the art of breeding a science. That “sports” and varieties 
that bred true had been known from a very early time is certain, but 
confused ideas as to variation among breeders and a superstitious devo- 
tion first to fixity and then to fluidity of species among biologists 
prevented their importance being recognized. It remained for Prof. 
Hugo de Vries of Amsterdam by his elaborate researches and experi- 
ments to clear up the confusion, classify the different kinds of variation, 
define mutation and unite characters and establish mutation as the 
chief material for the plant breeder. 
A mutation is a definite variation in the character of a plant that 
is at once inherited. These occur rarely — in most species they have 
never been observed, in a few they are comparatively frequent. A 
plant may mutate in different ways and the same species may mutate in 
the same way at different times and places. The new form's will cross 
with the parent or with each other exhibiting Hie laws of hybrids. 
A mutation, in short, is a species whose origin we know. 
The theory of unit characters found in the work of Mendel and of 
de Vries an endorsement that if it did not establish it as a fact at 
least placed it in the position of a working hypothesis. This is the 
conception that the characters of living organisms are due to definite, 
indivisible units whose identity persists from generation to generation. 
Unit characters or determinants are to the biologist what atoms are to 
the chemist, but we know much less about them. Matter is conceived 
