If such gradations were not all fully preserved, transitional varieties would merely appear as so many new, though closely allied species. 查尔斯·达尔文.物种起源.
The plate shows all gradations of intensity--the tidy is dark, the black tie is light. 伯莎M.克拉克.科学通论.
The idea is to break up the surface into various sized dots, as the various gradations of color on the original cannot be transferred by any other method to a sheet of copper and etched. 佚名.神奇的知识之书.
And all these gradations can be actually traced. 查尔斯·达尔文.物种起源.
That is to say, that the color changes imperceptibly in subtle gradations of light and shade. 佚名.神奇的知识之书.
Many subsequent improvements have been made, one type of which employs a succession of rolls which act in pairs on the grain one after the other and reduce it by successive gradations. Edward W. Byrn.十九世纪发明进展.
The _nothing_ of conversation has its gradations, I hope, as well as the _never_. 简·奥斯汀.曼斯菲尔德庄园.
Gradations of structure, with each stage beneficial to a changing species, will be favoured only under certain peculiar conditions. 查尔斯·达尔文.物种起源.
He was so old and his face was very wrinkled, so that a smile used so many lines that all gradations were lost. 欧内斯特·海明威.永别了,武器.
The gradations from leaf-climbers to tendril bearers are wonderfully close, and certain plants may be differently placed in either class. 查尔斯·达尔文.物种起源.
So that I think there is little in the advice of making those changes by easy gradations. 本杰明·富兰克林.富兰克林自传.
Mr. Busk, however, does not know of any gradations now existing between a zooid and an avicularium. 查尔斯·达尔文.物种起源.
We should be extremely cautious in concluding that an organ could not have been formed by transitional gradations of some kind. 查尔斯·达尔文.物种起源.