ABSORPTION FROM THE SKIN, THE LUNGS, ETC. 397 



absorption of all gases except ammonia and volatile substances. This is 

 illustrated by the rapidity with which anesthesia may be accomplished by 

 breathing the vapors of ether or chloroform. 



Solutions injected into or otherwise brought into contact with the sub- 

 dermal connective tissue, the surface of the body of a muscle, or intra- 

 muscularly, or within the peritoneal or thoracic cavities, very quickly pass 

 into the general circulation. They are practically injected into the lymph- 

 atic intercellular spaces in these instances and, of course, are very readily 

 carried through the lymphatic vessels, figures 280 and 282, to the thoracic 

 duct and into the blood. Readily diffusible substances, however, pass 

 directly through the blood capillary walls and do not necessarily follow the 

 longer lymph channel route. Comparing the rapidity of absorption in the 

 cases mentioned, that from the muscle is most rapid, a fact of medical im- 

 portance in the use of the hypodermic needle for the giving of medicines 

 in emergency. 



