The Chromosomes are responsible for heredity and variation and they control development. Their study has therefore become necessary for teaching and research in all parts of the life sciences. This book attempts to show how they have to be handled for such purposes. Chapters include: Origin; Equipment; Living Chromosomes; bulk fixation; smears and squashes; paraffin methods; staining and mounting; special treatments; the control of Mitosis; the control of Fertilization; Photography; Autoradiography; Describing the Results; 5 Appendices and Glossary of terms.