IRON COMPOUNDS IN ANIMAL AND VEGETABLE CELLS. 257 
This would seem to indicate that they are not constituted of 
typical chromatin.! I have endeavoured to determine whether 
they contain iron in a “ masked” form; but the results of my 
experiments, except in the case of B. megatherium, have 
not been decided enough to permit a general conclusion on 
this point. The organisms are very small, and their size 
would postulate the occurrence of a very small amount of iron 
in them, and even in the larger spores. When, therefore, a 
cover-glass preparation of B. megatherium is treated with 
sulphuric acid alcohol for twenty-four hours, it is not surpris- 
ing that the subsequent treatment with an acid ferrocyanide 
solution should give but a very faint blue reaction. When the 
granules referred to were under observation they manifested 
themselves by a blue colour slightly deeper than that apparent 
in the rest of the protoplasm of the organism. In B. subtilis 
the granules are the only parts of the bacillus which appear to 
contain iron, the reaction for which is very faint. I have in 
none of these forms obtained a reaction with the glycerine and 
sulphide mixture distinct enough to permit certainty of opinion 
in regard to this. Sulphate of iron, when present in very 
minute quantities in preparations, appears less distinct than the 
same amount of iron when revealed by the Prussian blue 
reaction, and on this account the apparent absence of the 
sulphide reaction determines nothing. In some preparations 
of B. pseudosubtilis the largest granules and the spores 
gave, after treatment with acid alcohols, a blue reaction with 
the acid ferrocyanide mixture. The root bacillus gave fre- 
quently a diffuse and faint blue reaction under the same condi- 
tions. 
It is obvious that these organisms are too minute to furnish 
results which would allow the question, whether they contain 
“masked ” iron, and how it is distributed, to be definitely and 
decisively answered, and I had to employ other forms, of such 
a size that no difficulty would be experienced in this respect. 
1 Vandevelde (“ Studien zum Chemie des Bacillus subtilis,” ‘Zeit. fiir 
Physiol. Chemie,’ vol. vill, p. 867, 1884) states that he has isolated nuclein 
from B. subtilis. 
