290 On Corpuscles of the Cornea, de. By G. F. Dowdeswell. 
exact point for this, a few minutes too much or too little rendering 
the preparation useless. If the time of exposure is too short, 
obviously the ground-substance is not wholly dissolved, and nothing 
is seen; if it is too long, the potash begins to act upon the pro- 
toplasm, and the corpuscles cannot be separated nor distinguished. 
It was found that, if the cornea was put into a 20 per cent. 
solution of pure potash cold, and then subjected to a temperature 
of 40° C., fifty minutes was the proper time required for the action 
of the potash. 
When sufficiently acted upon, the cornea is transferred to 
slightly acidulated water, to stop any further action of the potash, 
then placed on a slide, if necessary teased out lightly, and pre- 
served in glycerine. 
Ina preparation made by the above methods, a number of migra- 
tory cells will be apparent under the microscope, some of which 
are entangled amongst the processes of the fixed corpuscles. All 
these are in a state of active cell-division and assuming diversified 
forms, but are very readily distinguished from the fixed corpuscles 
by their being devoid of processes, of somewhat darker colour, and 
by their presenting a more opaque and solid appearance.* The 
fixed corpuscles, with their processes, show no alteration whatever. 
As may be seen from the Figures (Plate CLXXXIV., Group II.), 
the processes radiate from the bodies in a natural and symmetrical 
manner, and the ramifications are as perfect as ever. This would 
certainly not be so if segmentation had occurred; for in that case 
one side at least of each newly divided corpuscle would be devoid 
of processes. Nothing approaching to such a condition is ever 
seen. In inflamed preparations, as in normal ones, fixed corpuscles 
are occasionally met with containing two nuclei or a double. 
nucleus; but this appearance is not often seen, and not more fre- 
quently in later than in earlier stages. 
In conclusion, it may be stated that in the whole number of 
successful preparations of corneas which have been examined 
(amounting to upwards of twenty), no single instance has occurred 
in which any distinct appearance of segmentation can be made out. 
The most careful scrutiny of the preparations fails to detect any 
difference whatever, as regards their forms or aspects, between the 
fixed corpuscles of inflamed corneas and those of normal corneas — 
prepared in a similar way; nor would it be possible to distinguish 
preparations of the two classes from each other, were it not for the 
presence of migratory cells in the inflamed structure. 
In the drawings representations are given both of normal pre- 
parations (Plate CLXXXIV., Group I.) and of others at the most 
active period of inflammation (Group IJ.). These have all been 
most carefully drawn under the camera, each fibre and line being 
* This is not adequately shown in the drawings. 
