Bird's-eye view

A photographer's study of the humble egg and nest

''Petrified Eggs and Nest'' (top) and ''Emu Eggs'' (below) are among the photographs by Rosamond Purcell at the Harvard Museum of Natural History.

CAMBRIDGE - It's a putdown to describe something as being "for the birds." The 32 photographs in Rosamond Purcell's "Egg & Nest" suggest there should be a comparable term, "from the birds." It would be anything but a putdown. How could it be? Purcell's pictures of these quintessential avian products are that distinctive, that elegant. The show runs through March 15 at the Harvard Museum of Natural History.

It's no surprise Purcell would photograph specimens of eggs, nests, and preserved birds (all from California's Western Foundation of Vertebrate Zoology). She's long demonstrated her affinity for the natural world - more specifically, the collected natural world. She's a lot closer, in fact, to Joseph Cornell than Eliot Porter. Nature, per se, doesn't interest her. Nature's artifacts do. What murder scenes were for Weegee, specimen cases are for Purcell: an aesthetic home away from home.

As it happens, eggs and nests are themselves a kind of home. Another thing they have in common is, of course, birds. Beyond that, they fascinatingly diverge.

An egg comes from a biological process. A nest is as much the product of construction as any log cabin - or, for that matter, birdhouse. (One of the most striking images in "Egg & Nest" shows a birdhouse that's been covered over by a paper wasp nest.) What starts with reproduction ends in architecture - and starts all over again, what with nests being where eggs are both laid and hatched. Which came first: the nest or the egg? Let's just say it's a bird-brained question and leave it at that.

In texture, the two are even more different. Eggs are porcelain-smooth, with the seamlessness of a theorem. Nests are rough and twiggy and vigorously makeshift. How makeshift? One of the unexpected pleasures of "Egg & Nest" is keeping track of the various materials used in nest-making: plastic, string, scraps of newspaper, audio tape, nails, even bits of fireworks. Surely, Kurt Schwitters was part bird, and bricolage must be every ornithologist's preferred form of art-making.

Where eggs and nests diverge most may be aesthetically. The ad hoc, thingy beauty of nests is great. The very nearly Platonic beauty of eggs is even greater. Nature offers few purer forms than their life-nurturing curvature. Even so, geometry defers to decoration. The delicate speckling on Murre eggs, as recorded by Purcell, is a kind of calligraphy beyond calligraphy. Its precise filigree mocks what mere ink and brush might do.

With Charles Darwin's 200th birthday so recently observed, it's not just blinkered but undiplomatic to speak of Intelligent Design. Perhaps, though, there's a similar concept evident in Purcell's photographs both science and religion can agree on. Call it Spectacular Design.

Mark Feeney can be reached at mfeeney@globe.com.