34 The Selection Theory 
bees—the Lamarckian factor may be excluded altogether, for it can 
be demonstrated that here at any rate the effects of use and disuse 
cannot be transmitted. 
But if it be asked why we are unwilling to admit the cooperation 
of the Darwinian factor of selection and the Lamarckian factor, since 
this would afford us an easy and satisfactory explanation of the 
phenomena, I answer: Because the Lamarckian principle is 
fallacious, and because by accepting it we close the way towards 
deeper insight. It is not a spirit of combativeness or a desire for 
self-vindication that induces me to take the field once more against 
the Lamarckian principle, it is the conviction that the progress of 
our knowledge is being obstructed by the acceptance of this fallacious 
principle, since the facile explanation it apparently affords prevents 
our seeking after a truer explanation and a deeper analysis. 
The workers in the various species of ants are sterile, that is 
to say, they take no regular part in the reproduction of the species, 
although individuals among them may occasionally lay eggs. In 
addition to this they have lost the wings, and the receptaculum 
seminis, and their compound eyes have degenerated to a few facets. 
How could this last change have come about through disuse, since 
the eyes of workers are exposed to light in the same way as are those 
of the sexual insects and thus in this particular case are not liable to 
“disuse” at all? The same is true of the receptaculum seminis, which 
can only have been disused as far as its glandular portion and its 
stalk are concerned, and also of the wings, the nerves tracheae and 
epidermal cells of which could not cease to function until the whole 
wing had degenerated, for the chitinous skeleton of the wing does 
not function at all in the active sense. 
But, on the other hand, the workers in all species have undergone 
modifications in a positive direction, as, for instance, the greater 
development of brain. In many species large workers have evolved, 
—the so-called soldiers, with enormous jaws and teeth, which defend 
the colony,—and in others there are small workers which have taken 
over other special functions, such as the rearing of the young Aphides. 
This kind of division of the workers into two castes occurs among 
several tropical species of ants, but it is also present in the Italian, 
species, Colobopsis truncata. Beautifully as the size of the jaws 
could be explained as due to the increased use made of them by the 
“soldiers,” or the enlarged brain as due to the mental activities of 
the workers, the fact of the infertility of these forms is an insur- 
mountable obstacle to accepting such an explanation. Neither jaws 
nor brain can have been evolved on the Lamarckian principle. 
The problem of coadaptation is no easier in the case of the ant 
than in the case of the Giant Stag. Darwin himself gave a pretty 
peeea 
