Sentence:  They were great architects deeply enmeshed in an urban chain of innovation; Wright <WSD>riffed</WSD> on Sullivan's idea of form following function, and Sullivan <WSD>riffed</WSD> on Jenney, and Jenney relied on the fireproofing innovations of Peter B. Wight. 
Meaning of the word marked with <WSD> tags:  To improvise in the performance or practice of an art, especially by expanding on or making novel use of traditional themes.