IRON COMPOUNDS IN ANIMAL AND VEGETABLE CELLS. 197 
third, fourth, and fifth extraction resulted in the same way. 
When, on the other hand, a quantity of crystallised hemo- 
globin was acted upon by the reagent for forty-eight hours at 
35° C., the filtered fluid, tested for iron in the manner 
described, gave a scarcely appreciable evidence of the presence 
of the metal. The iron, therefore, which is found in animal 
tissues after the use of Bunge’s fluid at either 35° or 50° C. 
for short intervals cannot very well be supposed to be derived, 
in any appreciable quantity, from the hemoglobin in them, and 
as ammonium hydrogen sulphide does not affect the iron of 
the pigment, yet reveals the iron of “ masked ” combinations of 
an apparently less firm character, it follows that weak solutions 
of hydrochloric acid at slightly raised temperatures must attack 
such combinations more readily than it affects hemoglobin. 
This was most clearly shown by results of experiments on 
hemoglobin and chromatin with a quantity of Bunge’s fluid 
for twenty-four hours at 35°C. When hemoglobin alone is 
thus treated, neither the powder nor the extract gives any 
appreciable indication of free iron, but the latter is readily 
demonstrable in chromatin, or in mixtures of chromatin and 
hemoglobin, after similar treatment. Since the iron in 
hemoglobin is not affected to any perceptible degree by treat- 
ment with the reagent for twenty-four hours at 35° C., one 
may postulate that it is as little affected by treatment with 
either of the other two acid alcohols at the same temperature, 
and experiments with these have given results which bear out 
this conclusion. 
The substance chlorophyll, the relations of which to iron, 
though generally recognised, have not been definitely deter- 
mined, is, as is well known, an abundant constituent of the 
cells in many vegetable forms, and, therefore, a brief discussion 
of the possibility that this substance is the source of the iron 
demonstrated in vegetable cells, is necessary. 
Some of the more recent investigators of this substance have 
made conflicting statements on the question of the presence of 
iron in the molecule. Adolph Hansen! found it to contain 
1 ‘Die Farbstoffe des Chlorophylls,’ Darmstadt, 1889, p. 58. 
