When about 200 students showed up for Natural Sciences 135, "Man's Impact on the Environment," it was "quite a surprise" to the instructor, James N. Butler, Mckay Professor Applied Chemistry.

When Butler last offered the course, in the fall of 1978, about 65 students enrolled. He was expecting about the same number this time.

"I had given up hope" of attracting a large number of students to the course, Butler said this week.

To accommodate the crowds, Butler hired four new section leaders during the past two weeks, bringing the total to six. Lauren Zeise, who is teaching two sections for the course, said yesterday the average section size was 30 students.

Trying to explain the sudden appearance of 140 more students than the teaching staff expected, Zeise said, "There must be a much greater environmental awareness than we thought."

But Edward T. Wilcox, director of General Education, suggested yesterday some different reasons for Nat Sci 135's popularity. He noted the dearth of Nat Sci courses this semester-only three-and a "tendency for people to avoid science courses with a lab."

While Nat Sci 135 has no lab sessions, all the Core science courses offered this semester do. Wilcox said some students "show hesitation about going into the Core because of a fear of science courses."

Wilcox is the administrator who predicts-"I make a guess," he said-how many students will take Gen Ed courses the following year. What went wrong with Nat Sci 135? "I guessed way off. The students faked me out," he said.