Professor Frank Baxter and some animated friends answer questions about blood. what makes it red? Why do little animals' hearts beat so quickly? And so much more.
| Directing | Frank Capra | Director |
| Directing | William T. Hurtz | Director |
| Writing | Frank Capra | Writer |
| Editing | Frank P. Keller | Editor |
| Production | Joseph Sistrom | Associate Producer |
| Production | Frank Capra | Producer |
| Camera | Harold E. Wellman | Director of Photography |
| Directing | Arthur S. Black Jr. | Assistant Director |
| Sound | Archie Dattelbaum | Sound Effects |
| Visual Effects | William T. Hurtz | Animation Director |
| Visual Effects | Shamus Culhane | Animation |
| Sound | Raoul Kraushaar | Music Supervisor |
| Production | Nancy Pitt | Researcher |
