236 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 
From the first growth of the tree, many a limb and branch has decayed 
and dropped off; and these fallen branches of various sizes may repre- 
sent those whole orders, families, and genera which have now no living 
representatives, and which are known to us only in a fossil state. As 
we here and there see a thin straggling branch springing from a fork 
low down in a tree, and which by some chance has been favored and is 
still alive on its summit, so we occasionally see an animal like the 
Ornithorhynchus or Lepidosiren, which in some small degree connects 
by its affinities two large branches of life, and which has apparently 
been saved from fatal competition by having inhabited a protected 
station. As buds give rise by growth to fresh buds, and these, if 
vigorous, branch out and overtop on all sides many a feebler branch, 
so by generation I believe it has been with the great Tree of Life, which 
fills with its dead and broken branches the crust of the earth, and 
covers the surface with its ever-branching and beautiful ramifications. 
DIFFICULTIES AND OBJECTIONS TO NATURAL SELECTION AS 
SEEN BY DARWIN 
Long before the reader has arrived at this part of my work, a crowd 
of difficulties will have occurred'to him. Some of them are so serious 
that to this day I can hardly reflect on them without being in some 
degree 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 the 
theory. 
These difficulties and objections may be classed under the follow- 
ing heads: First, why, if species have descended from other species 
by 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 modifica- 
tion of some other animal with widely different habits and structure ? 
Can we believe that natural selection could produce, on the one hand, 
an organ of trifling importance, such as the tail of a giraffe, which 
serves as a fly-flapper, and, on the other hand, an organ so wonderful 
as the eye? 
Thirdly, can instincts be acquired and modified through natural 
selection? What shall we say to the instinct which leads the bee to 
make cells, and which has practically anticipated the discoveries of 
profound mathematicians ? 
