THE MICROSCOPE. arb) 
I have recommended the lactic acid to precede the stain with 
the chloride of gold, since this reagent serves best for dissolving 
certain chemical constituents at the border of the cornea, thus 
enabling us to split it into the very thinnest slabs without the 
least difficulty. Many experiments made for this object with 
other reagents, the action going on for months, proved to be fail- 
ures; whereas, with the acid which does not in the least change 
the structural minutiz of the cornea in its central portions not 
directly exposed to the acid, every single attempt at obtaining 
perfect specimens has been a success. 
I have advised the stain with a half of one per cent. solution 
of chloride of gold for two reasons. In the first place, since the 
introduction of this reagent by Cohnheim, in 1864, all microscop- 
ists agree to its value for dyeing protoplasmic formations or cells 
without destroying their anatomical relations. In the second 
place, I have shown, in 1872, that chloride of gold renders es- 
pecially plain certain parts of the protoplasm or the cells, which 
I recognized as the living or contractile matter proper. Thus, by 
resorting to chloride of gold, we gain in two respects, both as 
regards the distinctness of protoplasmic formations generally and 
the prominence of certain features within the protoplasm as well 
as the basis substance, showing the situation and distribution of 
the living or contractile matter. 
Let us place a slide, mounted according to my directions, under 
the microscope, first with a low power, not exceeding two hun- 
dred diameters. We see throughout the whole lamella dark violet, 
branching, so-called stellate bodies, representing, as all micros- 
copists admit, the “ cornea-cells.” In the slab under the micros- 
cope, be it ever so large, we shall never find any other but’ 
branching and interconnecting, dark violet cornea-cells, even 
though we may carefully study all the forty lamelle obtained 
from a single cornea. In vain will we look in the healthy cornea 
for an isolated lump, lacking connections with its neighbors and 
entitled to the name of a “ migratory cell,” at least this is my 
experience after having studied hundreds of cornea specimens, 
treated in manifold ways. The uppermost layer, containing the 
stratified epithelium, is worthless for us, since it is studded with 
granules of the metalic salt; so is the lowest layer. For the 
whole breadth of the substance of the cornea, respectively, all 
its lamelle that are perfectly free from granular precipitions of 
