Mad Scientist was a series of "mad science" toys released by Mattel. The original set with the Monster Lab and featured a vat with two plastic monster skeletons and an array of small parts like fangs, eyes, et cetera. One would apply this squishy and wet "monster flesh" to the skeletons. Then, water was added to the lab along with two packets of monster-flesh dissolving substance (one was citric acid). One would then place the monster in the vat and be delighted in watching the flesh be sizzled off the skeleton. Unfortunately, the flesh could no longer be used afterwards but one would be able to purchase small Monster Sets that had a unique monster mold and either more Monster flesh or Living Ice (which incidentally did not dissolve in the vat).
A second set that was available was the Dissect-An-Alien set that featured a small alien with a rubbery clear abdomen and a slit down the middle. One would fill its body cavity with several brightly colored organs and dump a generous amount of included Alien Blood (which was glow-in-the-dark). It also came with a playmat and a plastic knife. One would then pretend to dissect the alien and take pleasure in removing the goo-covered organs.