In the beginning both Looney Tunes and Merrie Melodies drew their storylines from Warner's vast music library (notice the names Looney Tunes and Merrie Melodies). From 1934 to 1943, Merrie Melodies were produced in color and Looney Tunes in black and white. After 1943, however, both series were produced in color and became virtually indistinguishable, with the only stylistic difference being in the variation between the opening theme music and titles. Both series also made use of the various Warner Bros. cartoon characters. By 1937, the theme music for Looney Tunes was "The Merry-Go-Round Broke Down" by Cliff Friend and Dave Franklin; the theme music for Merrie Melodies was an adaptation of "Merrily We Roll Along" by Charles Tobias, Murray Mencher and Eddie Cantor.
In 1929, WB became interested in developing a series of musical animated shorts to promote their music. They had recently acquired the ownership of Brunswick Records along with four music publishers for US $28 million. Consequently, they were eager to start promoting this material to cash in on the sales of sheet music and phonograph records. Warner made a deal with Leon Schlesinger to produce cartoons for WB Schlesinger hired Rudolph Ising and Hugh Harman to produce their first series of cartoons. Bosko was Looney Tunes' first major lead character, debuting in the short Bosko, The Talk-Ink Kid in 1929. The first Looney Tunes short was Sinkin' in the Bathtub which was released in 1930. When Harman and Ising left Warner Bros. in 1933 over a budget dispute with Schlesinger, they took with them all the rights of the characters and cartoons which they had created.
A new character called Buddy became the only star of the Looney Tunes series for a couple of years. With the animators working in the Termite Terrace studio, they debuted the first truly major Looney Tunes star, Porky Pig, who was introduced in 1935 along with Beans the Cat in the Merrie Melodie cartoon I Haven't Got a Hat directed by Friz Freleng. Beans was the star of the next Porky/Beans cartoon Golddiggers of '49, but it was Porky who emerged as the star instead of Beans. The ensemble characters of I Haven't Got a Hat, such as Oliver Owl, and twin dogs Ham and Ex, were also given a sampling of shorts, but demand for these characters was far exceeded by Beans and Porky; Beans himself was later phased out due to declining popularity, leaving Porky as the only star of the Schlesinger studio. This was followed by the debuts of other memorable Looney Tunes stars such as Daffy Duck (in 1937) and the most famous of the Looney Tunes cast, Bugs Bunny (in 1940).
Bugs appeared mostly in the color Merrie Melodies and formally joined the Looney Tunes crew with the release of Buckaroo Bugs. Schlesinger began to phase in the production of color Looney Tunes with the 1942 cartoon The Hep Cat. The final black-and-white Looney Tunes short was Puss n' Booty in 1943 directed by Frank Tashlin. The inspiration for the changeover was Warner's decision to re-release only the color cartoons in the Blue Ribbon Classics series of Merrie Melodies. Bugs Bunny made a cameo appearance in 1942 in the Avery/Clampett cartoon Crazy Cruise and also at the end of the Frank Tashlin 1943 cartoon Porky Pig's Feat which marked Bugs' only appearance in a black-and-white Looney Tunes short. Schlesinger sold his interest in the cartoon studio in 1944 to Warner Bros. and went into retirement, he would die five years later.
