| OCR Text |
Show CHAP. v. LAWS OF VARIATION. 170 ay be of ea ch slight difference Whatever the cause m . ts-and a cause for f then paren l . the offspring rom t dy accumulation, throug 1 1n · t · the s ea · 1 t each must exist-1 IS h differences, when beneficia o natural selection, of s?c . to all the more important the individual, that gives ris~ which the innumerable modifications of struc::se,ea~h are enabled t? struggle beings on the face of the best adapted to S1UVIve. with each other, and CHAP. VI. DIFFICULTIES ON THEORY. 171 CHAPTER VI. DIFFICULTIES ON THEORY. Difficulties on the theory of descent with modification-TransitionsAbsence or rarity of transitional varieties-Transitions in habits of life-Diversified habits in the same species-Species with habits widely different from those of their allies-Organs of extreme perfection-Means of transition-Cases of difficultyNatura non facit saltum-Organs of small importance-Organs not in all cases absolutely perfect-The law of Unity of Type and of the Conditions of Existence embraced by the theory of Nat ural Selection. LONG before having arrived at this part of my work, a crowd of difficulties will have occurred to the reader. Some of them are so grave that to this day I can never reflect on them without being staggered ; but, to the best of my judgment, the greater number are only apparent, and those that are real are not, I think, fatal to my theory. These difficulties and objections may be classed under the following heads :-Firstly, why, if species have descended from other species by insensibly :fine gradations, do we not everywhere see innumerable transitional forms ? Why is not all nature in confusion instead of the species being, as we see them, well defined ? Secondly, is it possible that an animal having, for instance, the structure and habits of a bat, could have been formed by the modification of some animal with wholly different habits? Can we believe that natural selection could produce, on the one hand, organs of trifling importance, such as the tail of a giraffe, which serves as a fly-flapper, and, on the other hand, organs of 12 |
