Aprit 19, 1912] 
in one strain until the rats were almost 
wholly black, and in the other strain al- 
most wholly obliterating the black. The 
speaker is not informed whether the in- 
heritance in hybridization of these appar- 
ently new characters has been tested. If 
a new character has been added it should 
maintain itself and segregate after hy- 
bridization. 
The experiments conducted by Dr. 
Smith and others at the Illinois Experi- 
ment Station on selecting high and low 
strains of corn with reference to oil and 
protein content, have resulted in markedly 
distinct strains possessing these qualities, 
which are inherited apparently as long as 
the selection is continued. It seems certain 
that the oil and protein content has been 
increased considerably beyond the maxi- 
mum which existed in the original race. 
The writer is informed by Dr. Smith that 
experiments have been made in cultivating 
these varieties without selection and that 
the new characters have been maintained 
for several years without marked regres- 
sion. We must apparently conclude then 
that new heritable characters have been 
acquired in the course of the selection, but 
it will probably be difficult to determine 
whether the advance is to be considered as 
a cumulative effect of the selection of fluc- 
tuations or the gradual purification by the 
selection, of mutants which occurred during 
the selection or possibly even before the 
first selections were made. The purifica- 
tion of a type even when the character con- 
cerned is easily observable is known to 
require a number of years unless both 
parents are carefully followed. Whether 
these qualities will segregate as unit char- 
acters after hybridization has not been 
determined so far as the writer is informed. 
Very many cases of increases obtained in 
quantitative characters could be cited, but 
the majority of the experiments were un- 
SCIENCE 
601 
dertaken primarily to obtain practical 
results, and whether such apparently new 
characters would stand the test of unit 
characters is doubtful. 
The improvement of the sugar beet by 
selection forms a typical and instructive 
case of this kind. The careful selection of 
the sugar beet was started over sixty years 
ago by Louis Vilmorin, at which time a 
range of variation in sugar content of from 
5 per cent. to 21 per cent. was known to 
exist. Since that time the industry has 
grown extensively until hundreds of thou- 
sands of beets are examined annually and 
the richest in sugar content selected for 
seed production. The process of selecting 
the beets richest in sugar content for 
mothers has now been continued for sixty 
years and is practised extensively every 
year, and yet there is no evidence that the 
maximum sugar content has been increased, 
and it is certain that the character of rich- 
ness in sugar content has not been rendered 
permanently heritable, as sugar beet grow- 
ers well know that their success depends 
upon the contimuance of the selection. 
Here it is certain that no distinct unit char- 
acter has been added by the continuous 
selection. 
The strongest evidence as to the method 
of origin of new characters is derived nat- 
urally from our knowledge of known cases 
of the origin of such typical new charac- 
ters. When we view the evidence critic- 
ally, I think it must be admitted that in 
practically all, if not all, of the cases of 
new characters appearing, they have come 
into existence suddenly. The cut-leaved 
Celedonium, the cupid sweet pea, Bursa 
heegeri, the Otter sheep, the muley cow, 
are illustrations familiar to all and doubt- 
less each of us could add several such illus- 
trations from our own knowledge. Such 
new characters appearing suddenly are 
heritable and maintain themselves as unit 
