When Toad first appeared in the X-Men back in 1964, his only mutant ability involved super-strong legs that allowed him to leap great distances. As the years went by, his mutation was enhanced and he gained a prehensile tongue, among other mutations.
When the first X-Men film was released, he displayed the ability to spit an adhesive slime, which he used on Jean Grey, nearly suffoating her to death. While this was the first time Toad had displayed this power, it migrated over into comics. My question is who was the first artist to do this? Any and all input is appreciated.