ORGANIC EVOLUTION—MACNAMARA, 877 
similar to the parent plant. Self-fertilized seed from these plants 
(1909) in 1911 produced plants exactly like those of 1907—i. e., 
fiowers having nine stamens and a style, but no petals. Self-ferti- 
lized seed from these plants are now (September, 1911) germinating 
freely. Some of the plants, however, of 1909, in place of a tall 
single spike, grew some seven or eight shorter spikes, each flower 
of which had nine stamens but no petals. 
Tt seems that a certain number of the Fox-glove seeds sown in 
the year 1906 contained elements in a condition such as that de- 
scribed by De Vries as beimg ‘‘impressed by an impulsive muta- 
bility,’’ for some of the flowers produced by these seeds were sports. 
Seeds from these sports produced their like in 1909; and, further, 
these latter plants bore some terminal flowers totally different in 
character from the parent sport from which they were derived. 
Seeds from these terminal flowers produced their like in the year 
1911, so that I have now two different strains of Fox-glove plants 
derived from the seed sown in 1906, and these strains have resulted 
from self-fertilized flowers—that is, from flowers carefully protected 
from insects or other means of cross fertilization. It is, however, 
doubtful if these varieties would have been maintained in a state 
of nature. While specific stability under constant conditions appears 
to be the rule in nature, it is widely different in cultivation. When 
a plant is brought under cultural conditions it maintains its type 
for some time unaltered, then gives way and becomes practically 
plastic. It is certain, therefore, that before we can accept De 
Vries’s hypothesis of the origin of species by mutation we must 
have further and more conclusive evidence on the subject than that 
which is now available. On the other hand, Huxley’s conclusion 
regarding the Darwinian hypothesis still holds good. He states 
that all species have been produced by the development of varieties 
from common stocks; the conversion of these, first into permanent 
races, and then into new species, by the process of natural selection, 
which process is essentially identical with that of artificial selection 
by which man has originated the races of domestic animals, the 
struggle for existence taking the place of man; and exerting, in the 
case of natural selection, that selective action which he performs in 
artificial selection. 
The evidence brought forward by Darwin in support of his theory 
is of three kinds. First, he endeavors to prove that species may be 
originated by selection; secondly, he attempts to show that natural 
causes are competent to exert selection; and, thirdly, he tries to 
prove that the most remarkable and apparently anomalous phe- 
nomena exhibited by the distribution, development, and mutual 
1 Nature, Nov. 28, 1907. 
