60 Miss M. P. FitzGerald. The Origin of the [June 4, 
Lepine (1872)* also repeated the injection experiment of Claude Bernard, 
and injected a dog with a solution of potassium ferrocyanide and a solution of 
lactate of iron by the left carotid artery, thus causing the animal’s death. 
Like Claude Bernard, he found a deposit of Prussian blue on the surface of 
the gastric mucosa, but after fixing the organ in Miiller’s fluid, in which 
Prussian blue, being insoluble, is unaffected, he obtained no evidence of its 
occurrence in the cells. 
This method failing, he altered the technique in a variety of ways, hoping 
by one or other process to prove the point in question. Thus, he macerated 
the stomach of an uninjected animal (dog) in full secretion in a solution 
of potassium ferrocyanide and lactate of iron; or, after death, macerated 
the stomach of a dog, previously injected with a solution of potassium 
ferrocyanide, in one of lactate of iron. Both methods gave negative results. 
Later, Lepine prepared a solution in which sulphate of iron and potassium 
ferrocyanide were present in the proportions and manner necessary for 
the formation of Prussian blue, and neutralised this with dilute caustic 
potash (litmus paper as indicator), thus causing the blue colour to disappear 
and the solution to become a dirty yellow. A drop of dilute hydrochloric 
acid added to several cubic centimetres of the fluid was sufficient to bring 
back the blue colour. In this solution he placed fresh sections of the 
stomach of normal dogs, killed by section of the medulla, one to three 
hours after the ingestion of a meal given after a fast of 24 hours. The 
contents of the stomach and the surface of the mucosa were in each case 
found to be acid to litmus. In some instances, before the meal, a dilute 
solution of bicarbonate of soda was injected into the stomach. Lepine argued 
that if acid were present in the glands, even if very dilute, the blue colour 
would appear in the sections when placed in the neutral fluid. The tissues _ 
were left in the solution for varying lengths of time, but a blue colour did 
not appear. . 
A portion of the mucosa detached from the outer coats of the stomach was 
also arranged as a dialyser, with an alcoholic solution of sulphate or lactate 
of iron on the one side, and an aqueous solution of potassium ferrocyanide 
on the other. Sometimes the dialysing solutions were varied, an aqueous 
solution of the iron salt being used, and a glycerine solution of potassium 
ferrocyanide. By this method a blue colour was invariably seen on the free 
surface after a certain number of hours, the degree varying with the method 
of procedure. The microscopical examination of the tissue, fixed in absolute 
~ alcohol, furnished no evidence of blue colour in the cells, but a slight deposit 
* R. Lepine, ‘Comptes Rendus,’ 1872, vol. 24, p. 221; and ‘Gaz. Heb. de Méd.,’ Paris, 
1873, p. 691. 
