562 Prof. B. Moore. Presence of Inorganic Iron 



the older the leaf is the more iron does it contain in its ash. Thus 

 Boussingault found in the ash of young leaves of Brassica 2 per cent, of 

 Fe20 3 , while old leaves contained in their ash 9 - 64 per cent. Zactuca sativa 

 had in the young leaves 2 - 67, and in the old leaves 6 - 43 per cent, of Ye 2 Os 

 in the ash. Another point is the curious conservation, resembling that seen 

 in the animal economy, of the iron of the leaf in the case of deciduous 

 leaves. Before the leaf drops a good deal of the iron is re-absorbed and stored 

 for future use. This is shown by analyses of the iron of the leaves of 

 Fagus sylvatica made by Bissmuller* in successive months. The figures 

 quoted give quantities of Fe 2 3 in 100 parts of dried leaves collected at the 

 times of year stated — 



May. June. July. Aug. Sept. Oct. Nov. 

 Oxide of iron 0'35 0-51 0'58 0"75 1-03 060 0-59 



The gradual increase of iron content to a maximum followed by a fall as 

 the leaves grow sere is very interesting. 



It has been shown by Molisch (loc. cit.) that iron is an essential constituent 

 for the growth of all plants, whether green or otherwise, but the saprophytic 

 and parasitic plants winch contain no chlorophyll require much less iron 

 and, as a rule, contain much less in their ash. Our own experiments show 

 that the histo-chemical reactions for iron develop much more slowly in the 

 fungi and are much less intense in degree. These feebler reactions probably 

 arise from organic compounds of iron slowly being decomposed in traces and 

 setting free ionic iron. These organic iron compounds of the fungi are 

 concerned with some other function than photo-synthesis or chlorophyll 

 formation ; they probably take a part in nuclear structures, for many nucleins 

 are iron-containing, and, as has been shown by Macallum, after treating with 

 acid alcohol to unmask the iron previously present in an organic form, the 

 chromatin of nuclei always contains iron. 



The reactions for inorganic iron are shown most markedly with the more 

 lowly organised plants such as unicellular green plants occurring alone or in 

 lichens, or in delicate algal threads, but when proper precautions are taken 

 they can also be clearly demonstrated in the chloroplasts of the higher 

 plants. The reactions are particularly well shown by the chloroplasts of 

 aquatic plants, where, as is well known, the percentage of iron in the ash is 

 also high. 



These facts are in keeping with the natural order of evolution and are 

 also in accord with other observations. For example, many algse (such as 



* "Ueber die Stoffwanderung in der Pflanzen," 'Landw. Versuchsstationen,' 1874 

 (' Just's Jahresbericht,' vol. 2, p. 849, 1874). 



