Does anyone remember an episode where the professor made a concoction out of plants to put invading cannibals/natives to sleep? Was it kava-kava??

To bump the oldest message on this (from May 2000!):
I'm not sure.

I think that you've got two Season 3 episodes mixed up here(clarifications are capitalised here:)
"Topsy Turvy" (Oct.1966?< the CAPTI-BORA berry extract which the Professor came u[ with to cure Gilligan's knock-on-the-head induced upside down vision, which made him rightly see right side up but was one many cures in life that can be worse than the disease, and Gilligan had, no thanks to the Prof., more than one other of those episodes!)

"Gilligan the Goddess" (the last aired episode, aired april 17, 1967, the strychnine used to put Gilligan to sleep and maybe a extract to "pacify"
one the lead headhunter so he wouldn't know what was going on, haven;t watched that one in ages)

To bump the oldest message on this (from May 2000!):
I'm not sure.

I think that you've got two Season 3 episodes mixed up here(clarifications are capitalised here:)
"Topsy Turvy" (Oct.1966?< the CAPTI-BORA berry extract which the Professor came u[ with to cure Gilligan's knock-on-the-head induced upside down vision, which made him rightly see right side up but was one many cures in life that can be worse than the disease, and Gilligan had, no thanks to the Prof., more than one other of those episodes!)

"Gilligan the Goddess" (the last aired episode, aired april 17, 1967, the strychnine used to put Gilligan to sleep and maybe a extract to "pacify"
one the lead headhunter so he wouldn't know what was going on, haven;t
watched that one in ages)

"Slave Girl" was the episode where the professor used something to put Gilligan under to fool the four natives, including Ugundi and the hot native chick.