The gorilla

I watched this last night on Chiller Drive-in. Admittedly, I didn't watch it very attentively. What's with the gorilla? At one point, a gorilla goes into the bedroom, I assume, of the lab assistant and scares her. I couldn't figure out how that fit into the flow of the film because she didn't seem to be affected by the incident very much. Or was that a different person? Was it the daughter the mad scientist wanted to snag for marriage? And what did the dog do in the scene?

What does the gorilla have to do with the scientist's research?

"Extremism in the pursuit of moderation is no vice."