Taking a new look at nature; Keith Country Journal, by John Janovy Jr., with illustrations by the author. New York: St. Martin's Press. $8.95 hardcover, $3.95 paperback.

You don't have to know a thing about snails or long-billed curlews or mosquito larvae to like this book. In fact, the less you know, the more you'll learn from John Janovy Jr.

Dr. Janovy is a cell biologist who studies the worms and parasitic protozoa that thrive in various bird, beast, and fish intestines. But wait -- there's more. He is also an admirer of beauty, a poet in laboratory smock, a professor who teaches students to love, a seer who poses some intriguing questions about the future of his favorite planet, Earth.

What the Galapagos Islands were to Charles Darwin, Keith County is to John Janovy. In this grassland corner of western Nebraska, where mastodons and bison once roamed, Janovy and his students now collect. They wade through vile marsh mud, and handle sodden logs as if they were new-born babes. They step softly, sit on banks with deer tracks, and write their thoughts. Pails and bottles filled, they drive the dusky road back to the lab and stay there through dinner, through early morning, till dawn, identifying mayflies.

The world of "Keith County Journal" is as familiar as the creek down the street, yet also far away, unknown, exotic. It is a world at which astute men "wonder," a world in which fish gills "captivate."

Because Janovy is moved by his work, so are we: ". . . the killifish chase has filled our lives with excitement and thrills, mystery and a sense of accomplishment, a hobby, a love, a very feeling that we are able to see the importance of the river as well as the cells on the green screen of the electron microscope."

Because his enthusiasm is tempered with pragmatism, we also appreciate the long- range implications: ". . . we have learned a lot about nature from our study of the fish and its gill community, but it is obvious from the newspapers describing transbasin water diversion schemes that we have a long way to go."

There is a beauty in this book -- seeing the Whitetail Creek headwaters for the first time, watching a recently fledged eastern kingbird -- and Janovy does a good job of sharing it with us. Although the written word does not always flow as smoothly as the Whitetail, it is conversational and genuine: "Salpinctes obsoletusm is a very plain name for a bundle of fire known as the rock hen." At times there is surprising poetry: "The heron and Frisbee flew together for a quarter of a mile, aerial formation duet."

Mathematician turned ornithologist turned parasitologist, Janovy is also something of a painter. With Turner as his guiding light, and netted magpies for models, he has brushed in some sprightly watercolor illustrations here.

But mostly, Janovy is a man with a quest. "A scientiest searches for truth about nature wherever that search may lead," he writes, "but a scientist also searches out of love and joy, for pride and money will not long sustain a search for the truth."

He remembers a day on a back porch in Louisiana many years ago, when he was four or five years old, when he squeezed a lizard to death. He especially remembers his mother's rage and sorrow and disappointment at what he'd done. She conveyed, he says, "a pretty substantial message of love for living things."

That message helps to explain some of Janovy's quasi-serious proposals for man's meetings with nature today. Giving duck hunters blank ammunition, he says , would be one interesting experiment. And, he asks, "might there be a role for a Labrador retriever other than going into the water after a deadm duck?"

If we are to learn from wild things, Janovy believes, the human must get into the wild as often as the wild thing is got into the laboratory. "Keith Country Journal" he hands us compass and trail guide and sends us on our way.

What will we find out there?

"No human has ever analyzed, or really ever known,"N the thoughts of a cliff swallow, so there is no way of knowing whether the swallow might also feel that it was made in the image of the creative force. But a future communication might well reveal that the cliff swallow feels it is unique, blessed with the image of the creator, and so must take care of the human." m