6 Preface 



the number of species in each phylum. (7) A consideration of the more 

 important types of the various orders of insects, including a simple key 

 for the identification of such forms with which the beginning biology 

 student might wish to become familiar, is given. (8) A summary of 

 the metamorphosis and life cycles of various types of animals and plants 

 is given to acquaint the student with this very important phase of the 

 living world. (9) The embryologic development of animals is illus- 

 trated by the frog because such demonstration materials are inexpen- 

 sive and easily secured. (10) The more important theories, laws, and 

 facts of heredity are discussed, with examples from the plant, animal, 

 and human fields. (11) A survey of representative animals of the past 

 and their records is made; a study of geographical distribution of 

 present-day animals in space, a survey of animal and plant ecology, 

 and a summary of the science of paleobotany are included. (12) Liv- 

 ing organisms are discussed as to their origins, continuity, development, 

 variations, and descent with change. (13) There are pertinent discus- 

 sions of the properties of living protoplasm, the structures and functions 

 of various cells and tissues, the process of cell division in animals and 

 plants, the differences between living and nonliving materials, and the 

 fundamental dififerences between living animals and plants. (14) There 

 is a comprehensive summary of the embryologic origin, distinguishing 

 characteristics, and- functions of the epithelial, connective, muscular, and 

 nervous tissues of animals. (15) A history of the development and 

 progress in the field of biology includes many contributions made by 

 earlier workers in the science. (16) A list of pertinent questions and 

 topics is found at the end of the chapters to teach the student to sum- 

 marize his knowledge, to more completely emphasize the important 

 points, and to stimulate the beginning student to do some original 

 thinking. (17) Suflficient emphasis is placed on the structures and 

 functions of the human body to be of value to students of physical edu- 

 cation, preprofessional students, and the general student who may or 

 may not take special courses in human anatomy and physiology. (18) 

 A separate chapter summarizes the more important theories and prin- 

 ciples of biology. From this the student may easily review and retain 

 those generalizations which will be of greatest use in his future activities. 

 (19) A special consideration is made of the application of biology in 

 various fields in order to show the contributions which this science has 

 made in the past and to suggest its applications in the future. (20) A 

 separate chapter is devoted to photosynthesis. (21) An appendix in- 

 cludes: (a) important prefixes and suffixes frequently used in biology 



