PREFACE 



The introductory biology course for which this 

 book is the laboratory manual comes in a period 

 of extraordinary changes. On the one hand, we 

 are undergoing a revolution in biology, which for 

 the first time is approaching its problems sys- 

 tematically at the molecular level. With the 

 emergence of biology at this level, already occu- 

 pied by chemistry and physics, science as a whole 

 has achieved a new unity. 



At the same time we are undergoing a funda- 

 mental revolution in American education. Its 

 main seat is not in the colleges, but the high 

 schools. Exhortations, threats, normal internal 

 developments, improved economic conditions, 

 federal programs for retraining teachers, science 

 fairs and competitions, and probably most im- 

 portant of all, the advanced placement program- 

 all these have had their effect, and students 

 now enter college in a very different condition 

 from what obtained just a few years ago. Many 

 of them know much more science and mathe- 

 matics than they ever did before. Indeed, many 

 of them have gone far past what we taught 

 juniors and seniors in the colleges only a few 

 years ago. 



What is much more important is that high- 

 school students quite generally have developed a 

 new eagerness to learn and understand science. 

 The glamor that used to go with athletic achieve- 

 ment seems largely now to be accorded scientific 

 achievement. The elation that students used to 

 derive from working their muscles, many now 

 seem to achieve also by working their heads. 

 Surprisingly learned, eager, responsive, deeply 

 interested — this is the new college freshman. 

 This book is dedicated to him. 



The course for which this book is the labora- 

 tory guide has been given on a reasonably large 

 scale to approximately 350 students, mainly 

 freshmen and sophomores, about evenly divided 



between general education students and those 

 intending to concentrate in the sciences, mainly 

 premedical students. No distinction whatever is 

 made in handling these two groups together; and 

 it is noteworthy that after a short initial lag, the 

 general education students keep up thoroughly 

 with the others. 



Each student has one three-hour laboratory 

 session weekly throughout two semesters. At 

 Harvard this comes out to thirteen sessions per 

 semester. Each laboratory section contains 

 about twenty-five students, supervised by two 

 graduate student assistants, and under the gen- 

 eral supervision of one of the senior staff who is 

 continuously available. In twenty-six laboratory 

 sessions we do everything described in this book. 

 It makes a keyed-up, busy laboratory, yet not a 

 harrassed one. If at any point we thought the 

 work of the laboratory was becoming too pressed 

 for time, we would cut down on its content. 



It may help place the laboratory work in 

 perspective to know something of its relation to 

 the lectures in our course. We have three one- 

 hour lectures per week through two semesters. 

 No attempt is made to synchronize the labora- 

 tory work with the lectures; each attempts to 

 develop its own logic. Nevertheless numerous 

 points of correspondence and overlap develop 

 between these two aspects of the course, and by 

 its end lectures and laboratory tend to form a 

 reasonably unified whole. Some idea of the con- 

 tent and sequence of the lectures can be gained 

 from the outline of lecture topics that follows. 



I. Origin of life (2 lectures) 

 II. Ultimate particles 



1. Interconversion of matter and energy 



2. Structure of the atomic nucleus 



3. Nuclear transformations: origin of 

 sunlight 



