The problems of aging and their correlation with senile changes as observed within the nervous system have been the object of extensive investigation. When interpreting microscopic observations on the senile nervous system one must bear in mind the following questions: 1. Do such structural alterations represent a normal senile involution of the nerve cell, or are they secondary to infectious processes, malnutrition and changes in blood supply?
2. Are these changes truly the result of antemortem degeneration, or do they represent postmortem autolysis?
3. Are they technical artefacts, such as shrinkage due to fixation in an acid solution of formaldehyde or to prolonged fixation in alcohol or vacuolation resulting from indiscriminate use of water at autopsy?
4. What is the nature of this senile change when observed with a variety of technics?
These and similar considerations account for many differences of opinion.
One of us (R. C. T.)1 has