Sentence:  There is an exquisite continuous gradation and <WSD>interlapse</WSD> of hue between the silver-grays, the reddish-browns, and the dull yellows of the honeysuckles, the ruddy apple, the auburn tresses of Venus, her lips and eyes, the red and pink roses, the yellow butterflies, and the dark-green background. 
Meaning of the word marked with <WSD> tags:  The distance between two things.