THE MUTATION THEORY 359 
on the mutation theory, the result of the appearance of new muta- 
tions. 
In consequence of this difference in the two theories, it will not’ 
be difficult to show that the mutation theory escapes some of the 
gravest difficulties that the Darwinian theory has encountered. 
Some of the advantages of the mutation theory may be briefly 
mentioned here. 
1. Since the mutations appear fully formed from the beginning, 
there is no difficulty in accounting for the incipient stages in the 
development of an organ, and since the organ may persist, even when 
it has no value to the race, it may become further developed by later 
mutations and may come to have finally an important relation to the 
life of the individual. 
2. The new mutations may appear in large numbers, and of the 
different kinds those will persist that can get a foothold. On account 
of the large number of times that the same mutations appear, the 
danger of becoming swamped through crossing with the original form 
will be lessened in proportion to the number of new individuals that 
arise. 
3. If the time of reaching maturity in the new form is different 
from that in the parent forms, then the new species will be kept from 
crossing with the parent form, and since this new character will be 
present from the beginning, the new form will have much better 
chances of surviving than if a difference in time of reaching maturity 
had to be gradually acquired. 
4. The new species that appear may be in some cases already 
adapted to live in a different environment from that occupied by the 
parent form; and if so, it will be isolated from the beginning, which 
will be an advantage in avoiding the bad effects of intercrossing. 
5. It is well known that the differences between related species 
consist largely in differences of unimportant organs, and this is in 
harmony with the mutation theory, but one of the real difficulties of 
the selection theory. 
6. Useless or even slightly injurious characters may appear as 
mutations, and if they do not seriously affect the perpetuation of the 
race, they may persist. 
CRITICISMS 
[Oenothera lamarckiana has fallen under suspicion of being of 
impure stock due to the crossing of two or more original species. The 
