416 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL. VIII. 
VI—THE IRON IN MUSCLE FIBRE. 
For the demonstration- of iron in the muscle fibres the reagent 
employed was hematoxylin, which has been shewn by Macallum to be 
a very sensitive one to determine the presence of iron in an inorganic 
combination. When inorganic compounds are treated with a 0.5 per 
cent. aqueous solution of haematoxylin the iron is represented by a blue- 
black reaction, but if the iron is present in the organic form no change 
in colour occurs. This latter may be converted into the inorganic form 
by the action of acid alcohol and when this is treated with the 
hematoxylin it gives the blue-black reaction above referred to. The 
acid alcoho] used for this purpose was one containing four volumes of 
concentrated sulphuric acid in 100 parts of absolute alcohol in which 
the tissue was left for at least fifteeen hours at a temperature of 35° C. 
This tissue was previously fixed in a four per cent. solution of formaline 
and, after all the formaline was removed by washing thoroughly in 
alcohol, was transferred to the sulphuric acid alcohol in which the 
preparation remained for fifteen to twenty-four hours at 35°C. All 
traces of the acid were then removed by washing with absolute alcohol 
and the fibrils finally stained in the hematoxylin solution for thirty 
minutes. They were then mounted in 50 per cent. glycerine. 
Using the aqueous hematoxylin alone on the fresh muscle tissue 
or on that previously fixed in alcohol or formaline there appeared in the 
fibrils only a slight yellowish brown coloration with a somewhat deeper 
colour in the narrow light band. The nuclei were stained a like diffuse 
yellow colour but with extremely fine darker granules scattered 
throughout (Fig. 13). 
Apparently the muscle fibril and the nucleus contain, if any, only 
an infinitesimal amount of inorganic iron. When the muscle has been 
treated with the acid alcohol and then subjected to staining with - 
aqueous hematoxylin solution a general, diffuse, faint purplish tone 
obtains in the dim bands, with more deeply stained, extremely fine 
granules irregularly distributed through them and what occupies the 
position of the narrow light band presents a very deep purplish colour 
(Fig. 14). In the nuclei the reaction is most intense especially along 
the chromatin threads (Fig. 15). When the myoplasm in which the 
fibril is embedded is not removed by the teasing, it takes a deep purple 
colour, equal in intensity to that obtaining in the light band, and the 
