Thanks for the correction in the role Lugosi played in the 1941 feature film. I had read that his part was as butler, so evidently the contributor online wasn't paying attention to the film.
The Black Cat ( 1934 ) was one of the early sound films to employ an almost continuous music score by Heinz Roemheld. In the way of leit motifs, R paraphrased Tasso by Liszt to serve as the theme for Werdegast. He did the same for Sonata in B Minor's recap section to underscore scenes that establish Poelzig. The film would suffer greatly without the music. His use of themes as leit motifs cover many scenes in the film to identify characters and locales. "Cat Love Theme", he slightly paraphrased from Tchaikovsky's Romeo and Juliet Love Theme and "Pathetique" ( movements 1 and 4 ). This is heard in the love scenes with the Alison couple and in some others with Werdegast and Poelzig.
If you print out the 1934 music page I authored and track the DVD of the film, you will see and hear it in a better sense. It was a painstaking task, but I loved doing it. Heinz loved the classics. Original compositions he employed were "Cat Threat" and "Emeline", which he named after his wife. Other original cues include "Cat Scream", "Cat Crawl" and "Morgue".
A shorter version of "Emeline" is heard early on in The White Hell of Pitz Palu ( Grapevine Video ) as the couple first go inside the cabin. A jaunty version of the cue was recorded for the Pitz Palu, but it didn't make it into the 1930 silent film. But, it was tracked in Destination Unknown's repeated cast credits.
Incidentally, all the music in The Black Cat was original. No tracked music in the score. An orchestra of only 28 musicians recorded it in eight hours with Roemheld as conductor. The organist was given nine hours for his material. The film had a high budget.
Roemheld's music tracked over to films such as Flash Gordon, Trip to Mars and features such as Werewolf of London and The Raven adds a significant impact in the cinematic quality of the films.