.1898-99.] STRUCTURE, MICRO-CHEMISTRY AND DEVELOPMENT OF NERVE CELLS. 417 
all animals and in well-stained sections is easily observed. Vacuoles are 
also quite frequent in the nucleolus, a fact which has attracted the notice 
of several observers. That this is quite correct is shown by the 
action of alkalies or of digestive fluids on the nucleolus. The action of 
digestive fluids in sometimes leaving a shell of undigested material has 
been referred to, but the effect of alkalies is more convincing. Held found 
that after prolonged treatment in the alkali the nucleolus no longer stained 
with methylene blue, and he thought that this showed that the nucleolus 
was formed of fine grains embedded in a ground mass. Alkalies have 
an altering action on the nucleolus similar to that on the Nissl granules 
but the action must be prolonged. If tissue which has been fixed in 
sublimate is used the action is very slow and one can often find the 
outer covering of the nucleolus broken, between the portions of which 
the oxyphile centre may be seen. This structure can be seen in sections 
stained with eosin and toluidin blue, or in iron-alum hematoxylin, but 
the clearest way of demonstrating it is the gold method of Apathy.” Figs. 
g and 10 are the nuclei of cells that have been treated with potash and 
then stained with this method. The oxyphile centre can be seen 
between the pieces of the basophile covering which has undergone frag- 
mentation. 
The above considerations render it clear that there are at least three 
distinct nuclein compounds in nerve cells, the Nissl granules, the baso- 
phile covering of the nucleolus and the oxyphile nuclear substance. Each 
of these bodies contains iron and phosphorus, the usual constituents of 
many nucleo-proteids. Van Gehuchten® and Cajal” believe the nuclein 
is condensed into the nucleolus, while v. Lenhossek maintains that the 
nerve cell does not contain true nuclein or chromatin. There seem to 
be many different nuclein compounds in different cells, but we shall see 
that for the nerve cells these different nuclein compounds are genetically 
related, and that intermediate substances are found in the nerve cells of 
different animals. 
49 Apathy, Stefan, ‘Das leitende Element des Nervensystems, etc,’’ Mitth. aus der Zool. Station zu 
Neapel, XII, p. 495, 1897. 
50 Gebuchten, A, van, “ L’anatomie fine de la cellule nerveuse, La Cellule, XIII, p. 313, 1897. 
51 Cajal. S. R., Revisto Trimensal Micrografica, 1896. (Original inaccessible, quoted from van 
Gehuchten). 
