Because of the Christmas period lull, you're getting a double whammy:
Attributions to follow. Both images are worth full points as if they were in separate posts. I won't be putting up the follow-up posts for each at the same time, so the second image will be open to challenge until its own post is up, not when the post for the first image appears.
Update: Identity of #41 now available here. Image from here. Identity of # 42 now available here. Figure from Chaimanee et al. (2004).
Sixty-four years later: How Watson and Crick did it
1 day ago in The Curious Wavefunction