A big problem with many modern horror films is the lack of practical effects. Often when things are done with CGI a persons brain can identify the fabrication. It interrupts the process of entering the world of the story and can often be the determining factor in a good/bad film. This is one major reason why Star Wars 1, 2 and 3 are such piles of garbage. It’s nothing but plastic looking textures on everything. Yet, done right like The Lord Of The Rings series or Jurassic Park and a person will lose themselves in a film.
The 1931 Dr. Jekyll and Mr. Hyde is a spectacle of how practical effects can be used to make an amazing scene. For the longest time the way this transformation scene was shot was kept a secret. The entire shot is so amazing and believable that it still boggles my mind. With the amazing acting of Fredric March and the use of the right makeups; this is by-far one of the best scenes in all horror history.