Gradually the historic phrases of descriptive micropathology such as "cloudy swelling" and "hyaline degeneration" give way to a rational appreciation of the molecular changes in cellular degeneration. Emotion suffers, but the intellect approves.
In the current milieu few theories have been accepted as wholeheartedly as de Duve's concept of the lysosome. This originally held that the lysosome was a local cytoplasmic collection of inactive lytic enzymes in liver cells confined within a membranous bag, which had to be ruptured before the enzymes became active. Since the idea was enunciated about ten years ago, it has been recognized both that similar bodies containing a variety of nucleases, esterases, cathepsins, and glycosides are present in many other tissues and that degradation of foreign substances can probably go on within the intact lysosome as well as outside.
In the first of the 15 papers that made up this symposium de Duve set the