They are the "hidden mothers": the blacked-out beings who hover behind their charges. These ghostly figures, their faces obscured, their identities forever lost, are the backbone of a new book that celebrates the late 19th-century vogue for photographing children in the manner of a portrait painter.
Such were the impracticalities of the task – slow exposure times and wriggly infants making for a particularly tiresome combination – that photographers had to find inventive solutions to get their shot. Most draped the "ghostmothers" in black sheets, lace curtains, or even (far right) some incongruous damask; though some photos show the odd nose, lowered eyelids, and arm after arm propping up the infants, most important was that these "ghosts" held their babes perfectly still.
Thus, what to our modern selfie-obsessed eye might look ridiculous was a triumph for a generation more used to posthumous portraiture due to high infant mortality rates.
The 1,002 photographs gathered by Linda Fregni Nagler in The Hidden Mother are all the more powerful for being viewed en masse. The Italian artist explains that her interest in this area of photography was first piqued by the manner in which an online seller labelled one of the images. "It was on eBay. The item up for auction was accompanied by the words, 'Funny baby with hidden mother'. I was immediately struck by the fact that the sales pitch included that which was excluded."
In an essay accompanying the book, Geoffrey Batchen, professor of the history of photography at the City University of New York Graduate Center, notes how the parents are "always effacing themselves in the interests of the legibility of the child. Fregni Nagler's work is about this effacement. It proposes that the gesture says something profound about the nature of parenting."
And indeed, what could serve as a better metaphor for parenthood than images in which the child takes centre stage and the mother – for they are unlikely to be fathers behind those shrouds – is scratched out, in the ultimate act of subjugation?
What's more, suggests Professor Batchen, because she is a woman, Fregni Nagler is the "ultimate subject, the hidden mother, of her own work".
'The Hidden Mother' is published by Mack, priced £40