"Femme Fatale" and "White Light/White Heat" and two songs where Cale played both viola and bass with Reed and Morrison on guitars: "Here She Comes Now" and "The Black Angel's Death Song", the former of which saw Cale doubling on piano. Although Morrison was a proficient bassist (as exemplified by his performances on "Sunday Morning", "Venus in Furs", "All Tomorrow's Parties" and "Lady Godiva's Operation"), he disliked playing the instrument. After Cale left the group in 1968, Morrison usually exclusively played guitar; however, photographic evidence indicates that he continued to play bass onstage for certain songs if Doug Yule, Cale's replacement, was occupied with organ. Additionally, Morrison frequently sang backing vocals and the occasional lead vocal spot (he recited many verses of Reed's poetry in "The Murder Mystery" and sang one line in "I'm Sticking With You"). Morrison repeatedly remarked that "Venus in Furs", from the band's debut album, was his personal favorite of all of The Velvet Underground's songs, as he felt that the group had achieved with that one track, to a greater degree than any other, the sound the band had in mind. In 1970, when the band was back in New York City to play an entire summer's engagement at Max's Kansas City, Morrison seized the opportunity to complete his undergraduate degree at the City College of New York. He remained in the Velvet Underground as lead guitarist after Reed left the band in acrimonious circumstances in August 1970. In 1971, however, he began graduate studies at the University of Texas at Austin, where he would earn a PhD in medieval literature (with a dissertation on the four signed poems of Cynewulf) in 1986. Morrison's last performance with the band was on August 21, 1971, at Liberty Hall (Houston, Texas). When it was time for the band to return to New York, Morrison packed an empty suitcase and accompanied them to the gate of their departing plane, before finally telling them he was staying in Texas and leaving the band, the last founding member to quit. Post-Velvet Underground life (1971–1990) Morrison began to work on Houston tugboats as a deckhand to supplement his income in the mid-1970s; when he was forced to relinquish his teaching assistantship some years later, he was licensed as a master mariner and became the captain of a Houston tugboat, a vocation he pursued throughout the 1980s. After leaving the Velvet Underground,