400 
pencils for widening the openings in 
glass tubes or finished parts, and the 
g I 
files for cutting glass tubes and rods. 
No iron molds of any kind are used for 
preparing glass models in the American 
Museum, but all parts are shaped free- 
hand from glass tubes and rods. Colored 
5 
glass is frequently used for the colored 
§ 1 : 
parts, but if the desired tints and shades 
of glass are not available, plain crystal 
glass is molded into shape and the colors 
g I 
applied later with the brush or with an 
air-brush. 
The process of using glass as a medium 
for representing animals will be realized 
Stages illustrating the modeling in glass of the microscopic 
animal Gonium. 
These little, single-celled creatures live in colonies of sixteen 
together, and there may be very many such colonies in a drop of 
water 
THE AMERICAN MUSEUM JOURNAL 
in some degree if we follow the construc- 
tion of a glass model — for example, 
that of a colony of the protozoan Gonium. 
From a glass tube of about one-half inch 
diameter, a piece about two inches long 
is separated by means of the blast lamp, 
blown in the flame to a cuplike shape 
and opened out to its whole width at 
one The gas flame is brought 
into action on the opening and the force 
of the flame will by itself enlarge the 
opening; but if the carbon pencil is 
rotated inside the heated area at the top 
of the cup this will flange it out more 
quickly. 
end. 
To imitate the coloring 
seen in the living Goniwm 
individual, which seems to 
shade from a deep green 
below to a light, almost 
transparent tint above, 
hundreds of little green 
glass particles are welded 
to the inner surface of the 
glass cup before it is wid- 
ened out, until the desired 
tints are secured. To do 
this a green-colored glass 
rod is broken up into small 
pieces and these are further 
ground in a mortar to the 
desired grain. A_ small 
quantity of these particles 
is strewn inside the cup 
which is then rotated in the 
gas flame until the green 
parts begin to fuse and ad- 
here to the wall of the cup. 
This process is repeated 
until the desired intensity 
of the color is secured. 
When the green particles 
are applied thickly the color 
ismoreintense; when scat- 
tered, a lighter tint results. 
After this the other parts 
of the animal such as nu- 
