ROBERTS, ON BLOOD-CORPUSCLES. Lyi 
they could be cracked by pressure under the microscope like 
starch-granules. More slowly the same destruction overtook 
the corpuscles spontaneously; and this significant fact was 
observed in the course of it:—sometimes the cell ruptured 
before the projection, the latter persisting as a bright granule 
amid or near the débris; sometimes, on the other hand (in 
the horse), the projection broke up before the dise to which 
it was attached. In this latter case the hood (if there were 
any) broke up first mto a scattered nebula of granular appear- 
ance, and then the nucleolus-like body within -burst into 
three or four bright fragments. (Fig. 2, d.) This train of 
events seemed to remove all doubt as to the complete isola- 
tion of the projection from the cavity of the disc. Last of 
all, the disc itself began to crack; in a few days all my spe- 
cimens were thus destroyed. 
In addition to magenta and tannin, the following sub- 
stances were tried, but they did not produce phenomena in 
the least analogous with the foregoing :—gallic acid, ferro- 
eyanide 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 observed 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 pig- 
ment. 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 magenta, the first thing observed is that the natural 
yellowish colour of the dise is discharged, and that a faint 
rose tint is assumed in its stead. The discs 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 
