1898-99. | STRUCTURE, MICRO-CHEMISTRY AND DEVELOPMENT OF NERVE CELLS. 411 
It has been shown by Macallum” that iron is a constant constituent of 
all chromatin. Mackenzie,* using the ferrocyanide method and the 
hematoxylin method of Macallum,™ found the Niss] granules to contain 
iron. Using the hematoxylin method, which consists in keeping 
sections in acid: alcohol (sulphuric acid 4, alcohol 100, by volume) for a 
few hours at 37° C., washing the acid out in alcohol and transferring 
them to an aqueous solution of hematoxylin, one finds the Nissl 
granules are stained bluish black, which is an indication that they con- 
tain iron. Besides the Nissl granules the nucleolus and the oxyphile 
nuclear substance have the same colour, showing that they also contain 
iron (Fig. 4). After the sections have been treated with the acid alcohol 
they may be transferred to acid ferrocyanide solution, when a Prussian 
blue reaction will be found in the three parts mentioned... The same 
resuit is obtained if teased-out cells are baked at 60° C. for several days 
in a mixture of ammonium sulphide and glycerine according to the 
method of Macallum, when the Nissl granules, nucleolus and oxyphile 
nuclear substance turn green, owing to the formation of ferrous sulphide. 
With any of these methods the Nissl granules are seen in the cell as 
masses ora reticulum. The appearances obtained by these methods are 
similar to those obtained by staining with toluidin blue alone, except 
that the oxyphile nuclear substance is also affected. 
Using the test for phosphorus as described by Macallum,” the Nissl 
granules, nucleolus and oxyphile nuclear substance give a marked re- 
action for phosphorus, while the intergranular spongioplasm gives a faint 
reaction. (Fig. 3). For the purposes of this test, material that has been 
fixed in alcohol is extracted in a Soxhlet apparatus and imbedded 
in paraffin. Sections fixed to the slide are washed several times in dis- 
tilled water to insure the absence of all alcohol, and then transferred to 
a solution of ammonium molybdate in nitric acid. After sections have 
been in this solution for some time they are brought into a solution of 
phenylhydrazin hydrochloride which reduces the phospho-molybdate to 
a greenish oxide of molybdenum but does not reduce the molybdate 
itself. Sections treated for a few minutes in the molybdate solution 
show little or no phosphorus. It is necessary to leave the sections in the 
molybdate solution for several hours in order to bring out clearly a re- 
action in the cell. After treating with phenylhydrazin hydrochloride the 
27 Macallum, A. B., ‘‘On the Distribution of Assimilated Iron Compounds, other than Hemoglobin 
and Hzmatins, in Animal and Vegetable Cells,” Quarterly Journal of Microscopical Science, Vol. 
XXXVIII, p. 175, 1895. 
* 28 Mackenzie, I. c, 
29 Macallum, A, B., ‘‘A New Method of Distinguishing between Organic and Inorganic Compounds 
of Iron,” Journal of Physiology, XXII, p. 92, 1807. 
30 Macallum, I. c. 
