The object of this research is to pursue the relations between collagen and ground substance of connective tissue. These entities which are so closely related morphologically and in part chemically, participate in all processes of tissue change: growth, remodelling, involution, injury and disease. We tend to study them in isolation rather than as an integrated system. "Mobilization" described a process of physiochemical change brought about by processes or agents, among them hormones, inducing organ growth or change. Tissues studies include periodontium, uterus, bone cartilage and skin. Modifiers include: growth, aging, pregnancy, enzymes, lathyrogens, injury. Methodologies include: histology and histochemistry using frozen and dried or cryostat-dried tissues exclusively; polarization optics on collage; biochemical extraction and identification of connective tissue components analytically or by radio-label; electron microscopy of ultrathin cyroscope-dried sections (experimental).