228 A. B. MACALLUM. 
rone layer (Kleberschicht) in the wheat-grain is richly supplied 
with a “masked”? compound ofiron. In some cells it is chiefly 
found in the large granules strewn through the cytoplasm ; 
in others, again, apparently it is wholly contained in the latter; 
while in certain instances, further, it was demonstrated only in 
the extreme peripheral portions of the large granules. This 
is most clearly shown in sections of the grain after they have 
been treated with sulphuric acid alcohol for twenty-four hours 
at a slightly raised temperature. When the individual cells of 
other sections are treated with the glycerine and sulphide 
mixture for several days the reaction for iron is readily ob- 
tained in their cytoplasm, but its localisation, as observed after 
the use of the other method, is thus less readily determined. 
The “masked” compound apparently belongs to the class of 
chromatins, for when sections are treated with the ordinary 
staining reagents the cytoplasm stains deeply, especially with 
safranin and hematoxylin, and the parts which are specially 
affected are those which correspond with the iron-holding 
structures in preparations treated with acid alcohols. 
Haberlandt! has made experiments upon the question of the 
site of origin of the diastase in the germinating rye-grain, and 
these appear to show that the ferment is elaborated in the cells 
of the gluten layer only. It is possible that the iron-contain- 
ing compound in the cytoplasm of this layer is the zymogen or 
prozymogen of the ferment. 
IV.—On tHe OccuRRENCE oF ASSIMILATED IRON ComPouNDS 
IN SPECIAL Forms. 
What I have said in the foregoing pages with regard to the 
presence of iron in the chromatin of higher forms of animal 
and vegetable life is true also in regard to the types of lower 
organisation in both kingdoms. In the investigation of the 
less highly organised animal and vegetable forms, however, 
1 “Die Kleberschicht des Grasendosperms als Diastase ausscheidendes 
Drusengewebe,” ‘Berichte der deutschen botan. Gesellsch.,’ 1890, p. 40. 
Abstract in ‘ Botan. Centralbl.,’ vol. xliii, p. 39. 
