Darwin's Theory of Sexual Selection 205 
continued during many generations, may at last have pro- 
duced an inherited effect on the vocal organs of the stag, as 
well as of other male animals? This appears to me, in our 
present state of knowledge, the most probable view.” 
Here once more we find that Darwin makes use, as a sort 
of last resort, of the principle of the inheritance of acquired 
characters. As long as the theory of selection, in any of its 
forms, appears to offer a satisfactory. solution, we find the 
facts used in support of this theory, but as soon as a diffi- 
culty arises the Lamarckian theory is brought to the front. 
It is this shifting, as we have already more than once pointed 
out, that shows how little real basis there is for the theory of 
sexual selection. 
The male gorilla has a tremendous voice, and he has, as 
has also the orang, a laryngeal sac. One species of gibbon 
has the power of producing a correct octave of musical notes. 
“The vocal organs of the American Mycetes cavaya are 
one-third larger in the male than in the female, and are won- 
derfully powerful. These monkeys in warm weather make 
the forests resound at morning and evening with their over- 
whelming voices. The males begin the dreadful concert, and 
often continue it during many hours, the females sometimes 
joining in with their less powerful voices. An excellent 
observer, Rengger, could not perceive that they were excited 
to begin by any special cause; he thinks that, like many 
birds, they delight in their own music, and try to excel each 
other. Whether most of the foregoing monkeys have acquired 
their powerful voices in order to beat their rivals and charm 
the females — or whether the vocal organs have been strength- 
ened and enlarged through the inherited effects of long- 
continued use without any particular good being thus gained 
—JI will not pretend to say; but the former view, at least in 
the case of the Hy/obates agilis, seems the most probable.” 
The odor of some mammals is confined to, or more devel- 
oped, in the males; but in some forms, as in the skunk, it is 
