RIGHT-HANDEDNESS AND LEFT-HANDEDNESS. 257 
the species be considered a useful character, though it is persistently 
inherited. 
Standing near me is a flower-pot, in which are several stalks of the 
common calla (I believe the botanical name is Richardia ethiopica) in 
bloom; and a little inspection shows that each spathe and leaf-bud is 
twistedinthesameway. If the leaf is held withthe point up and the 
upper surface toward you, the half of the leaf on your left is the part 
that formed the inside of the leaf-bud, and the margin of the leaf on 
your right is the part that formed the outside of the leaf-bud. This 
character is quite persistent in the specimens of this species found in 
this city, though I am told that a leaf twisted in the opposite way 
sometimes appears; while in the distinct species popularly called the 
black calla I believe the character is reversed. Now, does this 
persistence prove that the character in question is essential to the 
welfare of the species? Are we justified in assuming that natural 
selection is the cause of the persistence of such characteristics? Can 
anyone throw light on the subject that will make it easier to believe 
that the adaptation of the species would be in the least impaired if all 
the leaves and spathes were twisted in the reverse way? 
The usual method of meeting the natural inference from such cases is 
based on a double assumption, the first part of which is that natural 
selection is the only intelligible explanation of the modification of 
species or the persistence of character that has ever been given, and 
that if in any case we abandon this explanation, it is equivalent to 
abandoning all explanation; the second part of the assumption being 
that it is simply our ignorance of the facts that prevents us from 
recognizing the life-preserving results that are gained by the char- 
acteristic in question. This assumption ignores both the fact that 
species presenting characters of the kind referred to are found on 
every side, indeed that almost every species that fails to maintain com- 
plete symmetry of form is an example, and the fact that Darwin him- 
self pointed out another principle besides natural selection producing 
persistent characters. This principle of sexual selection he carefully 
distinguished from natural selection, showing that the results 
produced by it could never be produced by natural selection, and 
even maintaining that ‘‘It is not surprising that a slightly injurious 
character should have been thus acquired.”’ (The Descent of Man, 
2d ed., p. 601.) 
For my part I do not think much progress can be made in dis- 
covering where natural selection is the chief agent and where it is not 
the chief agent till we have carefully defined what we mean by utility 
and natural selection, and then adhere to our definitions. In my 
