568 Prof. B. Moore. Presence of Inorganic Iron 



yellow without any trace of red. The solution is then made up to 50 c.c. 

 and kept in a Jena glass flask, for the alkali which is slowly dissolved out 

 from ordinary glass rapidly turns the solution pink. The reagent should he 

 pale yellow when used, in order to obtain the best effects, and does not keep 

 in good condition for more than a few days. 



After the chlorophyll and fats have been removed from the tissue by 

 allowing it to stand in cold alcohol, or by boiling up with alcohol, the 

 colourless tissue must be well washed with water, and the water used must, 

 as described above, be doubly distilled from glass. 



The staining process may be watched in progress, when it will be found 

 that escaped chloroplasts from ruptured cells take on the stain first, and in 

 many cases show a deep purple-blue within a few minutes. Within the 

 intact cell the stain does not penetrate so rapidly, and the cell wall may 

 show a blue staining in ' some cases before the contained chloroplasts, but 

 eventually these also stain a deep blue, sometimes preceded by a dark 

 brown. The nuclei of the green plant cells also stain a deep blue (unlike 

 animal cell nuclei), and there is usually a much slighter diffuse blue in the 

 remaining cytoplasm. The fibres associated with the vascular bundles also show 

 in many cases a blue staining. This probably means that the iron salts are 

 carried along this route to the green cells. But the early and deep staining 

 of chloroplasts and nucleus are characteristic in the preparations. 



In addition to tissues containing chloroplasts, several preparations have 

 been made from plants not containing chlorophyll, such as yeast, moulds, 

 and larger fungi. There is a marked contrast found here, a blue stain does 

 not appear for some days, and then in only a comparatively feeble manner. 

 The conidia and the conidiophores show more iron than the mycelium filaments. 

 It is probable that this slow and feeble staining is due to organic iron 

 compounds slowly breaking up and yielding traces of inorganic iron. 



A series of ash analyses of chlorophyll-containing and chlorophyll-free 

 plants show in all cases a much higher percentage of iron in the ash of the 

 green plant ; these analyses will furnish the subject of a separate paper. 



A large number of plants of different types have been examined, and the 

 main results are given in the following account. 



Amongst unicellular green plants there were examined Chlorella, obtained 

 as plankton from a green-coloured pond water ; Phurococcus, obtained in 

 nearly pure condition growing on an oak fence near Oxford, and stained and 

 examined in collaboration with Mr. Edward Whitley; several forms of 

 diatom and several unicellular forms found in lichens. 



The blue-black effect is very readily obtained with these unicellular green 

 plants, often without previous removal of the chlorophyll. In the case of 



