THE AQUARIUM, OCTOBER, 1892. 13: 
acter of inflorescence favors promiscu- 
ous crossing, in which hybrids are con- 
spicuous ; but even here the number 
of individual hybrids is very small in 
comparison to the whole number of 
individuals. That is, the hybrids are 
rare, while the parents may be common. 
‘* Darwin was the first to show that 
crossing within the limitsof the species 
or variety results in aconstant revitaliz- 
ing of the offspring, and that this is 
the particular ultimate function of the 
operation. Darwin’s results are, con- 
cisely, these : self-fertilization tends to 
weaken the offspring ; crossing between 
different plants of the same variety 
gives stronger and more productive off- 
spring than arises from self-fertiliza- 
tion ; crossing between stocks of the 
same variety grown in different places, 
or under different conditions, gives bet- 
ter offspring than crossing between dif- 
ferent plants grown in the same place 
or under similar conditions ; and his 
researches have also shown that, as a 
rule, flowers are so constructed as to 
favor cross fertilization. In short, he 
found, as he expressed it, that ‘nature 
abhors perpetual self - fertilization.’ 
Darwin’s well-known experiments show 
that crosses between fresh stock of the 
same variety were nearly thirty per 
cent. more vigorous than crosses be- 
tween plants grown side by side for 
some time, and over forty-four per 
cent. more vigorous than plants from 
self fertilized seeds. On the other 
hand, experiments showed that crosses 
between different flowers upon the same 
plant gave actually poorer results than 
offspring of self-fertilized flowers. It 
is evident, from all his experiments, 
that nature desires crosses between 
plants, and, if possible, between plants 
grown under somewhat different con- 
ditions.” 
On the subject of ‘‘ producing new 
plants” Professor Bailey says: ‘‘ The 
second result of crossing, the summary 
production of new varieties, is the sub- 
ject which is almost universally asso- 
ciated with crossing in the popular 
mind, and even among horticulturists 
themselves. It is the commonest no- 
tion that the desirable characters of 
given parents can be definitely com- 
bined in a pronounced cross or hybrid. 
There are two or three philosophical 
reasons which somewhat oppose this 
doctrine, and which we will do well to 
consider at the outset. In the first 
place, nature is opposed to hybrids, for 
species have been bred away from each 
other in the ability to cross. If, there- 
fore, there is no advantage for nature 
to hybridize, we may suppose that 
there would be none for man; and 
there would be no advantage for man 
did he not place the plant under con- 
ditions different from nature or desire 
a different set of characters. We can 
overcome the refusal to cross in many 
cases by bringing the plant under cul- 
tivation where new conditions ‘over- 
power its former antipathies. Yet it is 
doubtful if such a plant will ever ac- 
quire a complete willingness to cross. 
In like manner we can overcome in a 
measure the comparative seedlessness 
of hybrids, but it is very doubtful if 
we can ever make such hybrids com- 
pletely fruitful. It would appear, 
therefore, that with plants in which 
fruits or seeds are the parts sought, no 
good can be expected, as a rule, from 
hybridization,- and this seems to be 
affirmed by facts. It is evident that 
species which have been bred away from 
each other in a given locality will have 
more opposed qualities than similar 
species which have arisen quite inde- 
pendently in places remote from each 
