F. Smith's offer of numerous specimens from the same nest of the
driver ant (Anomma) of West Africa. The reader will perhaps best
appreciate the amount of difference in these workers, by my giving not
the actual measurements, but a strictly accurate illustration: the
difference was the same as if we were to see a set of workmen building
a house of whom many were five feet four inches high, and many sixteen
feet high; but we must suppose that the larger workmen had heads four
instead of three times as big as those of the smaller men, and jaws
nearly five times as big. The jaws, moreover, of the working ants of
the several sizes differed wonderfully in shape, and in the form and
number of the teeth. But the important fact for us is, that though the
workers can be grouped into castes of different sizes, yet they
graduate insensibly into each other, as does the widely-different
structure of their jaws. I speak confidently on this latter point, as
Mr. Lubbock made drawings for me with the camera lucida of the jaws
which I had dissected from the workers of the several sizes.
With these facts before me, I believe that natural selection, by
acting on the fertile parents, could form a species which should
regularly produce neuters, either all of large size with one form of
jaw, or all of small size with jaws having a widely different
structure; or lastly, and this is our climax of difficulty, one set of
workers of one size and structure, and simultaneously another set of
workers of a different size and structure;--a graduated series having
been first formed, as in the case of the driver ant, and then the
extreme forms, from being the most useful to the community, having
been produced in greater and greater numbers through the natural
selection of the parents which generated them; until none with an
intermediate structure were produced.
Pages:
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297