Photograph copyrighted 1967 by Jim Marshall.
"This shot of Grace Slick and Janis was taken in 1967 for Teen Set magazine for an article on the two Queen Bees of San Francisco Rock. That morning I went over to Grace's house and then had to pick up Janis. Janis wasn't in the mood to do any pictures that day, but I begged her and she came along. Everyone always thought there was a huge rivalry between Janis and Grace, but they were dear friends. This is the only time they were photographed together, and by the end of the session, we were all getting pretty silly and clowning around." --From Not Fade Away, by Jim Marshall.
More info at Morrison Hotel Gallery.
Photo of Grace Slick being choked for 6/9 - Roger Ebert's Journal