436 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL. VI. 
hydrochloric acid. It is altered but not dissolved by acids and alkalies, 
which liberate the iron from it. The alkali acts much more slowly in 
removing the iron from this substance than from the Nissl granules. 
The three nuclein compounds of the adult nerve cell are derived from 
the mitotic chromatin of the primitive nerve cell. It follows from this 
that the Nissl granules are constituted of chromatin that has diffused 
from the nucleus into the cytoplasm. 
A substance analogous to that of the Nissl granules is found in the 
nerve cells of most animals, but not in all, as it is rarely present in the 
nerve cells of the Urodela. Those animals, whose nerve cells are devoid 
of this material, have chromatin in the nuclei of such cells similar 
to that found in the nuclei of the cells of other tissues. 
The Nissl granules are morphological elements of the cell, and consist 
of one substance. They have the same refractive index as the cyto- 
plasm during life, and are not found in the axis cylinder process. 
All the results obtained go to support the view that all iron-holding 
nuclein compounds are derived from pre-existing ones, and in mitosis 
all the iron-holding substance of the cell is confined to the nuclear chro- 
matin. 
