he comed in?

Well, if the author is Wilkie Collins, as stated, then the use of "comed" is hardly likely to vulgar slang for "ejaculated," unless he was writing Victorian porn, which I don't believe he did.

is hardly likely to vulgar slang --> is hardly likely to be vulgar slang

True, but I figured I'd bring it up because that is how you will hear the word used today.