- 1886] Microscopy. 529 
Now when water is allowed to flow into the reservoir mentioned 
above, the air is forced out through A into F, and thence along 
the tubes D and C into B and &. As soon as the pressure in 
these bottles becomes sufficiently great, the liquids which they 
contain will be driven out through the tubes Æ and Z. If there 
should be any obstacle to the escape of these fluid masses, the 
pressure in all the vessels will rise and be registered by the 
height of the mercury in 
If now it is desired to inject, for instance the kidney of a pig, 
a canula made of a glass tube must be fitted securely into the 
renal artery and a similar one into the renal vein. The canule 
must be of such a size that the rubber tubes, Æ and Z, will fit 
them well. Heat the gelatine masses in the bottles, 8 and X, to 
the proper temperature and keep them so heated until the injec- 
tion has been finished. Special care must be taken with the 
tubes, Æ and /, to prevent the gelatine passing through them from 
becoming frozen. Now having clamped the tube, Æ, have an 
assistant turn on a small stream of water until the gelatine begins 
to flow slowly from /, If the diameter of the canula is not too 
small it may be held with the free end directed upward and filled 
with gelatine allowed to drop from the mouth of Z. Then slip Z 
over the canula. Unclamp the tube, Æ, and when the gelatine 
from # has begun to flow, slip it over the canula inserted in the 
vein. Then increase the pressure gradually until it has reached as 
high a point as experience has taught to'be safe for the organ 
operated on. 
By means of this apparatus, which will require the expenditure 
of only a few cents and a little ingenuity, double injections may 
easily be made of any organs whose veins are not provided with 
lves. I have made injections of the kidney whose arteries and 
glomeruli became uniformly filled with the red mass and whose 
veins and the system of capillaries surrounding the renal tubules 
became filled with the blue. The lungs and the liver are easily 
and successfully injected. I have been less successful in injecting 
the organs that send away their blood current through the portal 
vein; but I have no doubt that they too may be injected. 
Triple injections of the liver may be made by first injecting the 
hepatic artery with a green mass until the whole liver assumes a 
green tint, and afterwards injecting the portal vein and the hepatic 
vein with red and blue as above directed. 
The same apparatus may be employed to make either single 
injections or the double ection described under the FEA 
head of this paper, by pi clamping one of the tubes, C or D. 
As a matter of course care must be taken that all the corks fit 
tightly in the bottles, otkeeihse the internal pressure may force 
them out at the very moment when an accident will do the most 
damage. 
VOL, XIX,—NO. V. 34 
