Adhering to the formula established in previous volumes of this pecular nature-photo series, the frog book presents the same basic material first in a businesslike introduction, then again in the shorter, simpler text that accompanies Bernard's closeup color photos (many underwater) of frogs mating, spawn rising, tadpoles developing, and new frogs eating and being eaten. In the similar book on chicken and egg, the introduction notes the increasing artificial use of ""intensive production systems,"" but the simpler words and photos, reasonably, have to do with a more natural barnyard existence. The book's showpiece, however, is a photo-sequence on the development of an embryo inside the egg. Here (and, to a lesser extent, in the frog book) the unattractive luminous color and the textured, veiny detail seem to be offering a close, clear look--but at what? Mostly glowing blobs, unexplained by the cursory captions and totally lacking the focus, direction, interest and sense of the Cole/Wexler A Chicken Hatches (1976).