140 COPE. [Vot. III. 
demonstrable fact. Change of structure acquired during life — 
as stated by Lamarck —is also a fact, though very limited. But 
the transmission of these latter changes to offspring is not 
proved experimentally ; all experiment tends to prove that they 
cannot be transmitted.” Two inferences may be derived from 
these statements. First, the author of them does not believe 
that the so-called congenital variations can be or have been 
acquired ; second, that he has no hypothesis to offer in explana- 
tion of the origin of congenital variations. These positions 
exclude another inference, which nevertheless may be derived 
from other propositions embraced in the abstract of the lecture. 
He says, with Lamarck, that ‘change of structure acquired 
during life is also a fact,” and also that “all plants and animals 
produce offspring which resemble their parents on the whole.” 
But in spite of these statements we are to believe that if a plant 
or animal acquires a useful addition to or modification of its 
structure during life, this is the particular variation which will 
not be transmitted. Since the modifications acquired by use 
during life are necessarily useful, it seems that according to the 
Post-Darwinians, the only way of acquiring useful variations 
known to us, is excluded from the process of organic evolution. 
To say the least of it, probabilities are severely taxed by such 
a position as this. 
But we say further, with Professor Cunningham, that were 
this hypothesis true, there would have been no evolution. If 
acquisition during lifetime is to render a character non-trans- 
missible, the continued growth of a single character by accre- 
tions during successive generations through geological ages 
could not and ought not to occur. Each generation should 
begin where its ancestors began in the matter of useful charac- 
ters, or those acquired by use, so that there could be no‘accu- 
mulation or development of such characters. The influence of 
the environment, as well as that of the energies of the living 
being, would be incompetent to develop more in a given gen- 
eration than that generation could acquire in its single lifetime. 
How then can evolution account for the law so beautifully dis- 
played by paleontology, of the gradual modification of parts 
through long geologic ages, towards given ideals of mechanical 
perfection? How can we account for the gradual perfecting of 
the articulations of the internal and external skeletons of those 
