The micro-incineration method (Raspail,1 Policard2 and Scott3), although not giving exact quantities, presents certain data concerning the relative distribution of ash in various parts of the normal nervous system (Scott3a and Alexander and Myerson4) and in various types of lesions in the pathologic nervous system (Alexander and Myerson4).
On the micro-incinerated slide normal gray matter appears rich, while normal white matter appears poor in ash (fig. 1). Allocortical areas (fig. 2 A and B) and the cerebellar cortex5 are richer in mineral ash than isocortical areas of the cerebral cortex (fig. 2 A). Cell groups in the process of development are richer in mineral ash than the same areas after complete differentiation, as can be demonstrated in the cerebellar cortex and the area striata (Alexander6).
These gross differences are explained by differences in mineral distribution in the various parts of the neuron
ALEXANDER L, MYERSON A. MINERALS IN NORMAL AND IN PATHOLOGIC BRAIN TISSUE, STUDIED BY MICRO-INCINERATION AND SPECTROSCOPY. Arch NeurPsych. 1938;39(1):131-149. doi:10.1001/archneurpsyc.1938.02270010141012