PROOFS OF EVOLUTION. 
21 
V. 
PROOFS FROM MORPHOLOGY. 
Convincing proofs of the truth of evolution 
are found in the homologies of animal structure. 
It may be well to distinguish this word, Homology, 
from Analogy, which refers to organs similar in 
form or function, but differing in origin, while 
. Homology relates to those parts or organs which, 
however dissimilar in office, were derived from 
one and the same part, modified and readjusted 
by use. For example, the wing of a bird and the 
wing of a butterfly are analogous, since they are 
both used for flying ; but they are not homologous, 
for they had not a common origin. But the wing 
of a bird, the fore-paw of a reptile or mammal, 
and the arm of a man, are homologous, since they 
have the same general structure, modified for 
different uses. Analogous parts look alike, but 
are not alike; while homologous parts may have 
little or no resemblance, but are in fact the same 
parts in disguise. 
Morphology, or the science which describes the 
