¿This book is a broadly historical account of a remarkable and very exciting scientific story¿the search for the number of human chromosomes. It covers the processes and people, culminating in the realization that discovering the number of human chromosomes brought as much benefit as unraveling the genetic code itself. 

With the exception of red blood cells, which have no nucleus and therefore no DNA, and sex cells, humans have 46 chromosomes in every single cell. Not only do chromosomes carry all of the genes that code our inheritance, they also carry them in a specific order. It is essential that the number and structure of chromosomes remains intact, in order to pass on the correct amount of DNA to succeeding generations and for the cells to survive. Knowing the number of human chromosomes has provided a vital diagnostic tool in the prenatal diagnosis of genetic disorders, and the search for this number and developing an understanding of what it means are the focus of this book.

Introduction.- Background to the Hunt for the Human Chromosome Number.- Microscopes and Stains: The Rise of Technology.- Mendel and Genetics.- Chromosomes as the Carriers of Heredity.- Difficulties of Chromosome Handling and Access to Material.- The Implications of DNA Structure.- Tissue Culture and the Cell Cycle: The Answer is Revealed.- The Flowering of Clinical Genetics.- Sex and Chromosomes.- What we Know, What we Don't and Where This may Lead us.- Appendix A: Rough Guide to Chromosome Structure.- Appendix B: People in the Text.- Glossary.

The author, Wilson Wall, has been a professional geneticist for more than 30 years, including postgraduate training as a clinical cytogeneticist. He has worked as team leader and section head as a clinical cytogeneticist in the UK, Australia and New Zealand. He carried out doctoral and postdoctoral research into areas of molecular genetics, specifically in evolution and forensic applications. For many years he was also secretary to the History Committee of the Institute of Biology.