Whitman added the poems from "Drum-Taps" and "Sequel to Drum-Taps" as a supplement to the fourth edition of "Leaves of Grass" printed in 1867 by William E. Chapin. Whitman revised his collection "Leaves of Grass" throughout his life, and each additional edition included newer works, his previously published poems often with revisions or minor emendations, and reordering of the sequence of the poems. The first edition (1855) was a small pamphlet of twelve poems. At his death four decades later, the collection included around 400 poems. For the fourth edition (1867)—in which "When Lilacs Last in the Dooryard Bloom'd" had first been included—"Leaves of Grass" had been expanded to a collection of 236 poems. University of Nebraska literature professor Kenneth Price and University of Iowa English professor Ed Folsom describe the 1867 edition as "the most carelessly printed and most chaotic of all the editions" citing errata and conflicts with typesetters. Price and Folsom note that book had five different formats—some including the "Drum-Taps" poems; some without.