30 ABSORPTION BY THE SKIN 



joints and tendons absorb very rapidly. Potassium prussiate 

 injected into the peritoneal cavity was found six minutes 

 later in the urine ; and strychnine similarly used caused 

 death in less than four minutes. Anaesthesia can be readily 

 induced in dogs by intra-peritoneal injection of chloral and 

 morphine. 



Drugs, even when volatile, pass very slowly and im- 

 perfectly through the unbroken skin, except when applied 

 with the assistance of an electric current (cataphoresis and 

 dielectrolysis), but absorption readily occurs from open 

 wounds and abraded skin surfaces. Clean-cut fresh wounds, 

 free from bleeding, absorb more rapidly than wounds which 

 are irregular, bruised, or bleeding. Absorption by granula- 

 tion tissue is less active, though occasionally undesirable 

 effects follow the careless application of toxic antiseptics to 

 wounds in process of healing. Drugs incorporated with oil, 

 lard, or lanoline, penetrate the skin more readily than do 

 ointments made with vaseline. Absorption of aqueous 

 solutions is hindered or prevented by the sebaceous matter, 

 but salts which are dissolved by the secretion of the skin 

 may produce general effects. Experiments prove that 

 agents which are soluble in sebaceous matter, or which 

 emit during their application vapour or gas, as guaiacol, 

 alcohol, benzine, potassium iodide, mercurials, carbolic acid, 

 etc., pass more or less rapidly through the skin. But the 

 intact epidermis of the horse, ox, and dog, offers considerable 

 resistance to penetration ; and in practice, lotions, liniments, 

 or ointments carefully used seldom endanger life. Slow 

 absorption may occur, but owing to more rapid elimination 

 the drug does not accumulate in sufficient quantity to excite 

 toxic symptoms. The subcutaneous areolar tissue absorbs 

 nearly as rapidly as the respiratory mucous membrane. 

 Hypodermic injections, properly prepared, are promptly 

 taken up unchanged by the blood-vessels and lymphatics. 



II. Between certain organs, tissues, or groups of cells, and 

 certain medicines, there appears to be a special elective 

 affinity. A medicine absorbed and in circulation, owing to 

 its chemical affinity, becomes arrested in contact with cer- 

 tain cell groups, where it fixes itself and tends to replace 

 some of the normal nutritive elements. From the common 



