Sentence:  It is a certainty that the windpipe of the larynx (l'anche du larynx), that is to say the little tongue (<WSD>languette</WSD>) or its opening, contributes more directly to the [performance of florid] passages and divisions than the other parts, in as much as it has to mark the degrees and the intervals which are made in sustaining the passage; which can only occur from the different openings of the little tongue (<WSD>languette</WSD>), as I have shown in speaking of low and high sound. 
Meaning of the word marked with <WSD> tags:  fleshy tongue-shaped structure