Sentence:  It was on account of she had such a happy temperament I persuaded Mr. van der Most to let me call her <WSD>Merry</WSD>. Lots of folks, when they first meet her, they think she's called Mary - Maria, as you would say it, Signor Lumaca - but no, her name is really <WSD>Merry</WSD>, M-E-double-R-Y, because, I always tell them, she "is". 
Meaning of the word marked with <WSD> tags:  (from=English) from the adjective, also a diminutive of Mercy.