ON INJECTING. 275 
The Lung. ‘The method of injecting the lung has been already 
described. A double injection is made by filling the veins first 
and the arteries afterwards, The veins should be handled very 
carefully, else, on account of their delicacy, they will be easily 
ruptured. 
The Brain and Spinal Cord are injected from the aorta. The 
cord requires very careful manipulation to dissect it out of the 
vertebral canal in such a way as not to injure it. <A pair of sharp 
bone forceps will be found very useful for cutting through the 
verterbree. 
The Tongue is injected through the carotid arteries. 
The Stomach is injected through the gastric artery. The veins 
of the stomach are to be filled by opening the portal vein, and 
directing the point of the syringe towards the stomach. 
The Intestines. The upper portion of the duodenum must be 
injected through the arteries which are derived from the cceliac 
axis ; the lower part of the duodenum, and also the ileum, the 
czecum, and the ascending and transverse colon must be injected 
through the arteries which are derived from the superior mesenteric 
artery. The descending colon, the sigmoid flexure, and the rectum 
are supplied with blood through arteries which originate in the in- 
ferior mesenteric artery, and must be injected through these arteries. 
In every case, if the vessels which pass to and from a part or an 
organ are large enough to admit the canula of the syringe, it is 
advisable to inject through them ; but if a vessel will not admit 
the canula, inject through that vessel of which the other smaller 
vessel is a branch. ‘The large vessel should of course be ligatured 
at points above and below that in which the pipe is inserted, or the 
injection will flow into adjacent parts. 
The Lymphatics. Ludwig’s puncture method is the simplest 
way of injecting the lymphatics. With a scalpel, make a slight 
incision in the pad of a dog’s or cat’s foot, and insert the nozzle 
of a hypodermic syringe, and inject Briicke’s Blue into the pad. 
Withdraw the syringe, close the cut with the thumb, and draw 
the fingers along the limb. ‘This will force the injection through 
the spaces in the connective tissue into the lymphatics. 
A little practice will soon enable the beginner to overcome the 
difficulty which attends the injecting of arteries; but it will be 
found that the veins, on account of their thinness and delicacy, 
require much more careful manipulation. A few failures may be 
expected at first; but after three or four trials, much of the 
difficulty of injecting will disappear. Careful dissection and 
attention to the directions here laid down will save much labour 
and loss of time. 
