Why a Book on Paramecium? Biologists usually concentrate their efforts on a single problem and a single organism. There is a difficulty with this practice, however, for as work on a problem proceeds it often becomes more ad vantageous to study the problem in another organism. Some biologists avoid the difficulty by moving from one organism to the other as the problem de mands. However, this tactic also has a disadvantage, for a thorough knowledge of the life cycle and thorough mastery of ways to handle a given organism in the laboratory are obviously of great importance to the researcher, and...