ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
683 
of its bottom is ft folded metal plate similar to those in aneroid baro- 
meters, and under this a sort of box, into which the gas passes through 
a tube. From this the gas passes by two tubes, one on either side, 
to a couple of burners. The heat from these burners passes up 
through the water through two metal tubes or chimneys. When heated, 
the excess of water passes out through an opening in the middle of the 
top, and when the desired temperature is attained the aperture is closed 
with a caoutchouc plug, into which fits a long glass tube open at both 
ends. Further expansion of the water causes it to ascend in the tube, 
and also to press on the metal plate, and as the latter descends it 
presses on the central gas-pipe, and thus stops off the superfluous access 
of gas. In this way the temperature of the thermostat remains quite 
constant. An additional power of regulating the supply of gas is ob- 
tained by means of a screw fitted to the pipe, by which it is brought 
nearer to the flexible metal plate. 
The author describes other apparatus constructed on a similar 
principle. 
(2) Preparing- Objects. 
Examination of Embryonic Liver.* — In his study of the liver of 
the embryos of mammals Dr. 0. Van der Stricht examined fresh tissue 
in serum and in different fluids ; teasing was effected in an aqueous solu- 
tion of 1 per cent, sublimate, 1 per cent, osmic acid, or Flemming’s 
liquid, and the elements stained with a dilute solution of safranin, 
methyl-green, or gentian-violet. Fixing was effected with an aqueous 
solution of 2 per cent, sublimate, either pure or with the addition of a 
little chloride of sodium, with Flemming’s liquid, either pure or with an 
equal part of water, or with Hermann’s liquid ; of these Flemming’s was 
found to be the best. The best colouring agents were safranin, gentian- 
violet, or Ehrlich’s violet. The finest preparations were obtained by 
using safranin and gentian-violet simultaneously. Imbedding in cel- 
loidin was found to be preferable to the use of paraffin. 
Preparation of Wing-muscles of Insects.j — Prof. E. A. Schafer 
cuts open a suitable insect and places it in alcohol of about 90 per cent, 
for twenty-four hours or more ; it is afterwards transferred into glycerin, 
when the sarcostyles of the wing-muscles can be isolated and examined 
without difficulty. When stained, as with haematoxylin, the dark bands 
take the staining most intensely, but the various parts of the sarcostyle 
differ in their behaviour to staining reagents. A very valuable method 
is to apply the gold-formic method to the tissue when taken from the 
glycerin. If fresh muscle be so treated the sarcoplasm alone is 
stained, but if the alcohol-glycerin muscle be taken, the reduction of 
the metal takes place in the sarcostyles and almost exclusively in their 
dark bands. By these means there may be brought out, with a clearness 
which renders the application of the photographic method comparatively 
easy, points of structure which, with our present usual methods of inves- 
tigation, have remained obscure. 
* Arch, de Biol., xi. (1891) pp. 41-2. 
f Proc. Roy. Soc. Lond., xlix. (1891) pp. 280-1. 
