Toyoichi Tanaka's pioneering work in biophysics made major contributions to the science of gels and polymers. His research centered on the physics of gels, their fundamental structures and characteristics, their dynamics, and their roles in living organisms. This volume collects twenty-five major research papers originally published in "Science, Nature, Physical Review Letters," and other leading journals between 1973 and 2000. The English texts are supplemented with Japanese summaries and critiques written by a group of Dr. Tanaka's colleagues and students.