The eye tends to perceive it only as smudge or sludge .
眼睛通常会仅将雾感知类似为一种斑迹。
I see a diapered black baby in a tree that 's only a green smudge under the water 's surface .
我看到一棵树上有一个包着尿布的黑皮肤婴儿，水面下的树就只是一个绿色的污点。
The smudge had been transformed into a more legible print : now , at least , there were the outlines of ridges and bumps .
该污迹已经转化成了一个更清晰的纹影：至少可以看出纹脊的轮廓和隆起部分。
But the subtle differences - a strip of white on the wing , a smudge of dark on the breast - set charles darwin on course to develop the most important scientific theory ever conceived : the evolution of species through natural selection .
