It has been pointed out by a number of experimentors, that after section of a nerve, certain chemical changes are demonstrable. A notable example is the presence of fat, formed by degenerative processes and shown by Marchi's osmic stain. Dr. Barratt in making quantitative analyses of the brain and cord in General Paralysis of the insane, which conditions is somewhat comparable to nerve section; so far as function is concerned, found also that there is a decrease in the percentage of phosphorus and an increase in percentage of water. Other, apparently degenerative, changes have been demonstrated by Dr. Bolton, who, in examining the prefrontal cortex of individuals who have suffered from various mental diseases, found, that in cases of severe Amentia the cells of the pyramidal layer could be distinguished by an experienced observer, but that the layer is only fairly well developed and very much more irregularly arranged than normally. It is not thicker, appreciably, than in the cortex of a still-born infant, and less than half as thick as in the normal adult brain. In severe Dementia the cells show normal characteristics, but all layers are decreased in thickness and the pyramidal layer is very much decreased. In general, no farther work has been done on chemical changes in the brain and cord (except in regard to phosphorus and water) possibly on account of the difficulty of obtaining material and, more especially, the lack of sufficiently accurate methods. The publication of a "Method for Quantitative Chemical Analysis of the Brain and Cord" by Koch, made possible a more thorough investigation of the chemical constituents of the Brain and Cord, and even of peripheral nerves, in pathological as well as normal conditions. With the knowledge of histological changes in various mental diseases and in sectioned nerves, a method of chemical analysis determined; this research was undertaken to discover if there are chemical changes corresponding to the changes in structure.