36 
MEMOIR OF LAMARCK. 
bitudes. It is susceptible of demonstration, that if 
species had an absolute constancy, there would be 
no varieties, but naturalists cannot help acknowledg- 
ing that such exist*. 
Whatever changes circumstances may have pro- 
duced in individuals, are all preserved by genera- 
tion, and transmitted to new individuals emanating 
from those which have undergone these changes. 
Unless this were the case, Nature could never have 
introduced the diversity among animals which we 
now witness, nor a progression in the composition 
of their organs and faculties - !. 
Such is Lamarck’s theory of life, and manner of 
accounting for the innumerable variety of forms in 
which living nature now appears. If his principles 
were once admitted, they would not only produce 
the effects he ascribes to them, but it would be 
a matter of surprise that natural productions are 
not infinitely more diversified than they really are, 
for nothing more is necessary than time and cir- 
cumstances for any one animal form to be trans- 
formed into any other, — for a monad or a polypus 
to become indifferently a frog, an eagle, an elephant, 
or a man. But the two suppositions on which they 
rest, viz. that it is the seminal vapour which orga- 
nizes the embryo, and that efforts and desires en- 
gender organs, are both so entirely arbitrary, and 
the latter so obviously fallacious, that very few have 
ever thought it worth while to attempt a formal 
* Aminaux sans Vertebrae, vol. i. p. 197, 198. 
+ lb. p. 199. 
