66 INTRODUCTION TO PHARMACOLOGY 



places of agents applied with fat or fatty substances for local pur- 

 poses. 



B. Enipidermic. Medicines placed upon and kept in contact 

 with the skin, no friction being used. (Solutions of the alkaloids in 

 oleic acid, chloroform. ) The agents pass through the skin with ease 

 by osmosis. Aqueous and alcoholic agents are but little absorbed in 

 this manner. Aqueous solutions are not absorbed from the skin 

 unless volatile or caustic, because the stratum corneum of the skin is 

 impermeable to water, and absorption from the skin must therefore 

 take place from the glands which prevent the absorption of water, but 

 not of other fat. 



C. Epidermic. Friction is used to promote the absorption or 

 passage of the medicant through the skin, as in the case of the mer- 

 curial ointments. 



D. Endermatic. Cuticle removed by blistering and the drug 

 powdered upon the surface. 



Relative Size of Doses. The following table shows the relative 

 size of doses for the different methods of administering medicines, 

 taking the oral dose as 1 : 



Mouth, 1 

 Subcutaneous, % 

 Rectum, 2 

 Intravenous, % 

 Intratracheal, 1/4 



Relative Doses for Different Species of Animals. Fish 

 gives the following table of doses : 



Horse, 1 Swine, Ys 



Cow, 11/2 Dog, Vie 



Sheep and goat, % Cat, %2 



These ratios are only approximate and one must take into con- 

 sideration the size of the animal and the effect of the different drugs 

 upon different species of animal. The doses for horses and cattle 

 are given as the same in most cases throughout the text, and of course 

 mean the average dose. 



HISTORY OF THERAPEUTICS 



Therapeutics probably dates back to prehistoric time, when man 

 cared for his own ills and those of his family and animals. He no 

 doubt chose his remedies from the surrounding vegetation much in 

 the same way as his food. That is, he tried many things in the hope 

 that some would be of benefit. The Bible contains many references 

 to medicine, and the Laws of Moses may be regarded in the light of 

 the first meat inspection law. 



