Compounds in Chloroplasts of Green Cells of Plants. 569 



the lichens the contrast is marked between the green cells and the fresh 

 hyphse of the fungus, but dead or decaying fungal matter often gives a 

 blue stain. 



The algae observed were species of Vaucheria, Spirogyra, Viva, and 

 Ulothrix. The effects were often repeated in several experiments, both with 

 hematoxylin staining and with ferricyanide and hydrochloric acid. The 

 ferricyanide solution does not appear to penetrate well, and only some 

 filaments in an alga like Spirogyra are coloured, but the staining has been 

 obtained within an hour or two of treatment with this reagent, and is a very 

 beautiful effect when obtained in Spirogyra. The light blue colour follows 

 the spirals of the chlorophyll bands, and the granules are obviously more 

 deeply blue than the rest of the bands. The deep blue-black with 

 hematoxylin is more readily and uniformly obtained, coming often within 

 a few minutes of applying the stain to the decolorised alga, and furnishing 

 again a beautiful effect. Sometimes, however, the brown colour of colloidal 

 iron is obtained in Spirogyra. 



Ulva latissima gives a very deep blue-black coloration, rendering the cells 

 almost opaque ; its ash shows a high content in iron. 



Cladothrix, when growing in water containing small amounts of iron, as is 

 well known, secretes, or excretes, a tube of iron oxide around the filaments, 

 and is then known as an "iron bacterium." When these so-called "iron 

 bacteria" are treated with hematoxylin, they turn blue-black almost 

 instantly, and, if the stained specimens are examined under the microscope, 

 the interesting fact is immediately observable that not only the external 

 tube, but the substance of the organism itself, is stained blue-black, so 

 settling a much disputed point. The same is seen in Vaucheria, an 

 incrustation of iron-oxide particles is demonstrable in the gelatinous sheath 

 surrounding the filaments, either by ferricyanide or hematoxylin staining, 

 but, in addition, both reagents show inorganic iron within the filament itself. 



Many higher aquatic plants, such as Lemna and Elodea, possess such 

 incrustations of iron oxide on their leaves when grown in water containing 

 only traces of iron, but in such cases it is also found that the chloroplasts 

 of the green cell itself are very rich in inorganic iron. The higher aquatic 

 plants examined have been these two and a variety of water-cress, and all 

 three were found to give a strong positive reaction. 



Ordinary lawn grass contains a high percentage of iron in the ash, and, 

 when teased out and deprived of chlorophyll by hot alcohol, forms a very 

 suitable object on account of the ease with which strands of fibre with 

 attached cells separate. The staining of the chloroplasts is at first a dark 

 brown passing later into a blue-black. The leaves of many species of 



