We may here remark that there is a most important 
difference between the elimination of the degenerate organ, 
when effected by various other causes, and when produced 
by Natural Selection. Experience shows us that disuse is 
sometimes accompanied by degeneration and sometimes 
not; that compensation and economy are sometimes 
active and sometimes not. Pangenesis may or may not be 
a true theory. The most ardent believer in these forces 
could only venture to assert that they are sometimes active. 
They may be efficient causes. And consequently we 
ought not to be surprised if we find in nature degenerate 
organs in every stage of reduction. But the case is quite 
different with Natural Selection, which asserts that the 
struggle for existence will not permit an animal to indulge 
in the luxury of possessing an organ, or the remnant of an 
organ, which is of no use. And Dr. Weismann is loyal to 
the logic of the theory when he contends that the final 
elimination of an organ will be produced by Natural Selec 
tion ; and yet clearly this elimination does not always take 
place. How, then, are we to account for this disappoint 
ment of a just expectation ? No answer, so far as I know, 
has been given to this question. The problem certainly is 
not solved by Mr. Darwin when, in opposition to all that 
he says elsewhere, he contends that degenerate organs 
being useless, will not be influenced by Natural Selection 
at all. 
“Variations, neither useful nor injurious, would not be affected 
by Natural Selection, and would be left either a fluctuating element 
or would ultimately become fixed, owing to the nature of the organ 
ism and the nature of the conditions.”—(Origin of Species, p. 63.) 
“ Rudimentary organs, from being useless, are not regulated by 
Natural Selection.”—(Origin of Species, p. 131.) 
“ Rudimentary parts, as it is generally admitted, are apt to be 
highly variable. . . . Their variability seems to result from their