Note 25 — THE VERBALIST. (continued 3)
Reading edition
"Some writers omit the comma in cases where the conjunction is used. But, as the conjunction is generally employed in such cases for emphasis, commas ought to be used; although, where the words are very closely connected, or where they constitute a clause in the midst of a long sentence, they may be omitted."—Bigelow's "Handbook of Punctuation."