260 THE AMERICAN NATURALIST. (VoL. XXXVI. 
THE Broap SIGNIFICANCE OF ANALOGY. 
We are familiar with the classic distinction of analogous 
organs as having a similarity of function: analogy (Owen, 
'43, p. 374), “a part or organ in one animal which has the same 
function as another part or organ in a different animal"; 
Lankester (70): * Any two organs having the same function 
are analogous, whether closely resembling each other in their 
structure and relation to other 
parts or not; and it is well to 
retain the word in that wide 
sense." Analogous organs 
may or may not be homolo- 
gous. “Analogy” is there- 
fore an extremely broad and 
comprehensive term, and it 
appears that we must include 
under it all cases of the similar 
evolution of organs either of 
common or of different origin 
due to similarity of function. 
For example, the * analogous 
variation" of Darwin, the 
pe ag insti ge wat roit n homoplasy" of Lankester 
B, Hyracotherium.. Not believed tobe genet- 1N part at least, the “ conver- - 
eme leneng dh ipo Pro on ea genz" of German writers, 
l the “homomorphy” of Für- 
bringer, the “heterology,” “parallels,” and « parallelism " of 
Hyatt, of Cope ('68, also Origin of the Fittest, p. 96), of Scott, 
and of most. American writers, are all illustrations of analogy 
and may be very misleading as to homology. 
As Scott observed in 1896, * Parallelism! and convergence 
of development are much more general and important modes 
| 1 The term “parallelism” was employed by Cope in his essay of 1868 on the 
CNN of Genera” (reprinted in the Origin of the Fittest) in two quite different 


