Ted Goranson considers the treatment of science in these movies:
In this first one, the scientist believes that if he understands how life works, he can heal the sick. He is a doctor, a medical doctor and studying what wouldn't be out of the ordinary today or even then. Only the experiment was unusual and grisly, messing with corpses, but even that isn't very far from ordinary.
In this second one, the nature of science has changed radically. A different writer, but the same filmmaker. It's no longer a quest for discovery; now the experiment has taken priority. We've added a new scientist, one clearly and visibly deranged. He's interested not in the discovery of the principles of the cosmos as they touch on life, but on the creation of artificial beings.
This time, the science is changed again. Now the scientific notion is back on discovery, but it's not about life from the human perspective. Now it is more cosmic, more celestial and yes, even godly. The son — who is smarter than his dad — knows that what his dad thought was the power in lightning was REALLY cosmic rays. They are the source of all life. So it isn't merely a matter of humanity, it is a matter of understanding god.
In this fourth one, we go through yet another change in how science is handled. Once again it shifts from the cosmic to the ordinarily human. It's about brains doing science and science on brains. We are reminded that the original scientist was not misguided, it was just his stupid assistant who made the mistake of using a "criminal" brain. Otherwise, all would be well. The doctor this time is a brain healer, and he has guess what? A dumb assistant who makes a critical mistake in substituting brains.
Also interesting is this observation about science in cinema from the post on the first film:
Science, and especially mathematics, is extremely cinematic to the people doing it, but I know of few films that seem to capture it well. The cinematic path seems to be through technological gizmos, and I think we have James Whale to thank for that. The lightning business wasn't central in the book... So it is something of genius to choose all those flying, vertical, sparking things. You can sense the energy. It's literally light, and the motif of light and dark in several literal and metaphoric threads throughout works with that.