A look at ‘hidden mother’ photos this Mother’s Day

Collectors relish so-called hidden-mother photographs as historical oddities. These 19th-century images contain very young children held still by half-obscured adults who crouch behind chairs or lurk at the margins of pictures, their protective arms stabilizing babies. The heads and shoulders of the adults are sometimes draped in textiles or summarily cut off, or their bodies are partially tucked behind decorative mats that frame the centered child. The startling realization...