THE YOUNG SCIENTIST. 
71 
plant to withstand this severe cutting 
back, the roots must be well-developed. 
Our climate is so dry, that unless the 
ground is deep the plants dry up and 
perish. The soil ought not to be too rich, 
but it ought to be very deep. 
The same rules apply to the shaping 
of plants into bowers or arbors. A screen 
that will exclude sun and rain can be 
formed only by severe cutting, so as to 
produce a dense mass of fine branches. 
Plaster Casts of the Face. 
ALTHOUGH this is an art which is 
usually practiced by sculptors, and 
artists specially prepared for executing 
such work, yet it is not a difficult pro- 
cess and may be easily carried out by 
amateurs. The best way, according to 
Stubchen-Kirchner is the following : First 
anoint the hairs, eyebrows, and beard— 
if the latter is to be preserved — very thor- 
oughly with pomatum or lard, until the 
hairs agglutinate, when they are to be ar- 
ranged exactly as it is desired they should 
appear on the cast. All other parts of the 
skin are then oiled, and the head isolated 
from the rest of the body by suitably ar- 
ranged cloths. A firm and well-waxed 
thread is now placed upon the head in 
such a manner that one half of it passes 
down the centre of the face, following the 
outline of the skin as closely as possible — 
and the other half passes over the back 
of the head, likewise closely following its 
contours. In the same manner another 
thread is passed over the head sideways, 
so that the whole surface is divided into 
four quarters. Good gypsum (dentist's 
plaster) is nOw mixed with warm water, 
the mass is allowed to become somewhat 
stiff, and then applied as quickly as pos- 
sible by means of a broad brush, be- 
ginning at the back of the head and end- 
ing at the mouth and nose. In order to 
facilitate breathing, paper-tubes may be 
inserted into the nostrils, but, with proper 
care and skill, this is not necessary. Upon 
the first layer a second, of much greater 
thickness is applied with the hands, and 
just as soon as the plaster begins to set, the 
ends of the strings are grasped with both 
hands, and pulled outwards and upwards, 
so that the cast is divided into four parts. 
After a short time it will have hardened 
sufficiently to permit its being taken to 
pieces. The pieces are then dried and 
varnished. When using them for making 
a cast, they are placed in position and 
luted together with plaster. Direct ap- 
plication of a thick layer of fresh plaster 
to the skin of the dead often produces un- 
natural shrivelling of the skin, or twisting 
of superficial organs. To avoid this, it is 
best to apply first a very thin layer of 
plaster, then a number of strips of very 
fine cotton or linen fabric, and, after this 
first thin layer is dry, to apply a thick 
layer of plaster on top of the latter. The 
preparation of casts after the moulds are 
made is so simple that it needs no special 
description. 
Pollen as Microscopic Objects. 
THERE is scarcely any class of objects 
that yields more beautiful and more 
easily prepared specimens for the micro- 
scope than pollen and seeds Later in the 
season we hope to tell our readers of the 
beauties of the latter, but at present the 
gardens and fields abound everywhere 
with pollen, and w^e shall turn our atten- 
tion to that. 
To examine pollen imder the micro- 
scope is not a difficult task. All we have 
to do is to shake a little on some smooth, 
dark surface, such as a piece of vulcanite 
or blackened paper, and examine it with 
a low or moderate power. The illumina- 
tion must be good ; good daylight answers 
well, but when we have to work at night 
we may get excellent results from the 
light of a good lamp condensed with a 
common condensing lens. The flowers of 
the hollyhock, the various lilies and other 
plants, all yield pollen differing widely 
in form, color, etc. It would occupy 
more room than w^e can spare to give the 
different appearances exhibited by the 
various pollens; we have selected four 
which will give a general idea of the 
beauty of this class of objects. 
In the engraving the pollen marked A 
is from the Althaea rosea ; B is that from 
Coboea scandens ; C from passion flower 
(Passiflora Caerulea), and D from Ifromsea 
purpurea. 
