The process of cellular death has received relatively little attention in recent years. Still, if we critically examine our present concepts of necrosis, necrobiosis, autolysis, or even necrolysis (GUILLEtr165 1939a) and necrophanerosis (MUEZL]~ 1955); and of the so-called degenerations preceding cellular death, with such time-honored names as cloudy swelling, hydropic degeneration, or new names such as pathobiosis (ALTMA~ N 1955), there can be no doubt that much of our knowledge pertaining to this field lacks in clarity.

This is not surprising, for the recognition of cellular death lies at the limit--and perhaps just beyond reach--of histological and histochemical methods. Suffice it to mention that the cells which we are accustomed to accept as normal in autopsy material have actually undergone not only death by acute ischemia, but also, in most cases, autolysis for several hours. This very fact, that cells may die without immediately showing any major distortion of their microscopic features, has allowed us to acquire most of our knowledge in the field of morbid anatomy. On the other hand, it has also brought about a peculiar shift in emphasis. The actual process of cellular death, the true catastrophy which is not witnessed in tissue sections, goes almost unmentioned, and the pertinent literature is very limited. In contrast, the secondary changes which transform a dead cell into an obvious lump of debris are brought into prominence under a special name, necrosis, and this topic has attracted considerable attention. The habit of studying tissues in fixed and stained preparations has also helped to eclipse the concept of cellular death. We have become accustomed to ignore the fact that in a tissue section all the cells are dead (ZoLr. r~ a~ R 1948a, GnOLL 1949, MUELLER 1955), and this again shifts the emphasis to necrosis, typified by the loss of the nucleus. As a matter of fact, in the contemporary literature, it is often apparent that the distinction between cellular death and necrosis has vanished altogether: the cell is assumed to die when it loses its nucleus. This misconception is to be found even in textbooks (SMIT~ et al. 1959).