1863.] 489 



tried, but they did not produce phenomena in the least analogous with 

 the foregoing: gallic acid, ferrocyanide of potassium, santonine, 

 sulphate of magnesia, alcohol and water, solutions of carbolic acid, 

 of atropine, morphia, iodine, sugar, gum, glycerine, and infusion of 

 coffee. 



A solution of picric acid produced the appearance of a parietal 

 particle like that brought out by magenta, except that it was not 

 coloured. An exactly similar appearance was on one occasion ob- 

 served in blood-corpuscles in the urine of a patient with acute Bright' s 

 disease. 



When magenta was applied after the process of pullulation had 

 taken place, the projections were found to take the dye strongly, and 

 especially the vesicular body within the hood. By this proceeding 

 beautiful and remarkable objects for microscopical examination were 

 obtained. In the fowl, dace, and minnow the projection was tinted 

 earlier than the central nucleus probably from its more ready access 

 to the pigment. The explanation of these appearances presents 

 great difficulties, and in the present state of the inquiry can only be 

 offered provisionally. 



The effect of the magenta-solution is not merely to tint, and so 

 render visible a very minute body. In watching the effect of ma- 

 genta, the first thing observed is that the natural yellowish colour of 

 the disk is discharged, and that a faint rose tint is assumed in its 

 stead. The disks at the same time lose their biconcave shape. The 

 parietal macula is rather "brought out" than revealed, and the 

 action of the solution is, to a very great extent, of a simply osmotic 

 character. 



The action of the tannin-solution is likewise in the main of a 

 similar nature, but modified in some very peculiar manner. Its first 

 operation is to cause the corpuscle to enlarge by imbibition, and this 

 goes on progressively until at length the cell is destroyed. If the 

 solution be strong, this destruction supervenes at once. The tannin 

 also unites with the cell-contents and coagulates them, imparting to 

 the corpuscle, finally, a solid consistence. The conditions of the 

 imbibition are disturbed by the previous application of magenta; 

 for no pullulation, or at most only traces, occurs when the corpuscles 

 are treated first with magenta and then with tannin. 



The bearing of these observations on the current views respecting 



