Berlin, Germany, Jan. 20, 1885.
—There are two ways of using the gelatine which has been prepared according to the method I described last week, viz: plate cultures and tube cultures.(a.) For plate cultures, which are especially useful to separate different forms of germs in a mixture, there is necessary an apparatus consisting of two bell-jars, a glass-plate, and glass-bridges. Of the bell-jars, which are about seven inches in diameter and two inches deep, one should be a trifle larger and a trifle less deep, to set over the other as a cover. The glass plate should be about six inches long and four inches wide, but this should be regulated by the size of the table to one's microscope stand, for we must be able to examine every portion of it by the microscope. The glass bridges should be such as to elevate the plate about