Sentence:  Tar and <WSD>cotton</WSD> him," said a student from the college, more facetiously, perhaps, more mercifully inclined. " Think, fellows, what a pretty bird he will be, with cotton for feathers ; — so downy." 
Meaning of the word marked with <WSD> tags:  To cover with cotton bolls over a layer of tar (analogous to (tar and feather) )