Seeing none, he nimbly leaps back to the other side and gazes into the water. Not bad for a man pushing 90.
Colleagues say not much has changed for the 89-year-old St. Mary's College biology professor who continues to teach 55 years after he arrived on campus and who still leads students on field trips into the hills.
"Most of the students don't have any idea how old he is," said Margaret Field, chairwoman of the St. Mary's biology department. "He's pretty hard to keep up with."
On Friday, the college will both honor Cory as its professor of the year and roast him. The Walnut Creek resident said he's torn between anticipation and dread.
Cory is miles away from the tweed-suited professors of his college days. His salamander forays demand denim jeans, shirt pockets jammed with pens and pencils, a windbreaker and sneakers that once were white.
"Our washing machine at home gets filled every few days with four pairs of muddy pants," Cory said as he drove his beat-up Honda sedan to a newt-breeding site near the St. Mary's campus. A fossil-laden rock he wanted to show his students rested amid a litter of dirt and leaves.
It would be an understatement to say Cory knows St. Mary's College.
When he was 10, Cory and his father attended the 1927 groundbreaking of St. Mary's Moraga campus.
Cory attended the college less than a decade later and joined the Christian Brothers, the Catholic order that runs St. Mary's. For nearly 40 years, Cory would be known as Brother Lawrence and wear the black frock of the order.
He received his bachelor's degree in zoology from Cal in 1942.
After a stint as a football coach at Sacred Heart Cathedral Prep in San Francisco, he completed his graduate studies in biology at the University of Notre Dame before returning to teach evolutionary biology at St. Mary's. He hasn't left since, although he did leave the Christian Brothers in 1972.
In the early 1970s, after finding traces of the pesticide DDT as high as 12,000 feet in the Sierra Nevada, Cory published evidence of DDT's effects on fly DNA in the influential journal Nature. Cory's studies led to testimony before federal lawmakers, which in turn led to a ban on the pesticide.
"I had this impression that all these politicians sitting up there reminded me of bull frogs," said Cory, ever the amphibian expert. "All they knew was how to get elected."
Cory said chemicals are more of an environmental risk than ever.
"There are all kinds of chemicals being synthesized all the time that never existed before," he said, standing in rubber hip waders next to a Moraga pond. "With most of these chemicals, we don't know what the effects will be on organisms, but it probably won't be good."
Cory is nearly a quarter of a century past the age when most people retire, but he doesn't plan to leave the college. Studies tell him that the aging human brain functions better when it's challenged, so he plans to continue splitting time between the classroom and the field.
"I like teaching, I like the students," he said. "I want to drop dead in the middle of teaching."
Former students remember him fondly. Concord resident Richard Smith said Cory was the best teacher he ever had.
"He kind of cracked the whip, but when you got out of his class you really knew what the class was about," the retired physician said. He took his first Cory class in 1959. "When I got to medical school, it was easier than being in his class."
This semester, Cory is teaching one class -- biology for nonbiology majors. Although he has relished his influence on students with medical-school plans, he has warmed to his current role.
"I'm getting more interested in teaching nonscience majors," he said. "People are more and more being called upon to vote on scientific issues, and the population in general doesn't understand science."
The lighter-than-usual schedule has allowed him to delve into intriguing genetic differences he has found among local newts, which are species of salamanders. He returns nearly daily to several streams and ponds to check on the newt population, wading among the reeds to find the jellylike egg sacs left by the amphibians, which resemble rubber lizards. Occasionally, he will snip a tiny piece of newt tail for DNA testing.
His renewed research focus, Cory said, has limited another hobby: making violins. A hand injury forced him to give up his longtime love of playing them, but he is trying to craft the instruments out of madrone wood.
Despite Cory's range of interests -- he also has made beer and helped prompt the college to take up its distinctive Great Books Program -- he is revered primarily as a scientist
Cory was "the court of last resort" in the early 1970s, the person on campus who could answer any biology question, said St. Mary's alumnus Steve Edwards, who directs the Tilden Regional Park botanical garden.
"We looked at him almost like he was another Gregor Mendel," Edwards said, comparing Cory to the father of modern genetics. "It was a wondrous thing to have this person walking around in a Catholic order's habit and know he was a world-class geneticist."
Field marvels at Cory's probing intellect and willingness to adapt.
"When you look at someone who doesn't get stuck in their method of research, then you know you have a scholar," she said. "He has a lot to teach all of us."
Old age and decades of accomplishments aside, Cory has no intention of spending more time in his cramped Brousseau Hall office than necessary. His most immediate concerns are the newts, most of which have not returned to local waterways this breeding season as in past years.
Standing next to the Moraga stream, he watched as a male salamander climbed a steep bank, waiting for the clumsy amphibian to tumble back into the water. Normally, he said, the animals would climb into the hills much later in the spring.
"I don't know where he thinks he's going," Cory said. "Maybe he says, 'There are no girls, so I'm going back to the sticks.'"
Matt Krupnick covers higher education. Reach him at 925-943-8246 or firstname.lastname@example.org.
Go online to see an audio slideshow of Lawrence Cory at work.
NAME: Lawrence Cory
OCCUPATION: Biology professor at St. Mary's College.
RESIDENCE: Walnut Creek
CLAIM TO FAME: His research helped prompt U.S. government to ban the pesticide DDT in the 1970s.
QUOTE: "I've come to think that teaching is, if not the most important thing a person could do, it's one of them."