INTRODUCTION 9 



fat are penetrant — such as alcohol, benzene, turpentines, 

 phenols, and alkaline liquids. The latter point is im- 

 portant. An alkali saponifies a fat and emulsifies it, and 

 thus alkaline solutions of phenols, and of arsenic, such as 

 are used in dips, may penetrate and cause danger if the 

 solution is too strong, or if it is left too long in contact. 

 Very little arsenic would be absorbed from a solution of 

 equivalent strength in an acid liquid. 



Absorption from the broken skin or from a wound is 

 naturally far more rapid than from the intact surface, and, 

 varying with the nature of the wound, approximates to 

 subcutaneous injection. The difference is well illustrated 

 by Kaufmann's figures for the toxic doses of powdered 

 arsenious oxide for the sheep, which are by the mouth 

 75 grains, and by application to a wound 3 grains. 



(c) The alimentary tract offers a more suitable mucous 

 surface, external to the body, than the skin,, forming a very 

 extensive, moist surface, covered by a delicate epithelium, 

 and is the most usual channel of absorption of a poison. 

 In contradistinction to the stomach and intestine, the 

 membranes of the mouth and gullet are thicker, and 

 swallowed materials do not rest in contact with them for 

 very long, so that absorption by this channel is of less 

 importance than from the stomach and intestines. 



Among carnivores the stomach offers an acid medium to 

 the ingested materials, thus favouring the solution of 

 substances sparingly soluble in water, but yielding soluble 

 salts with hydrochloric acid. Such are the majority of 

 alkaloids, and many metallic oxides — e.g., those of lead, 

 barium, zinc, and mercury. Absorption takes place freely 

 from the stopiach of a carnivore. Thus, Taylor quotes 

 results obtained by giving strychnine wrapped in paper 

 to cats and dogs. In the case of a dog, death resulted 

 after some considerable period — longer than three hours — 

 and f of a grain of a dose of 2 grains had been dissolved. 



In the horse absorption from the stomach is not so rapid 

 or complete as in the carnivores. Thus, Smith* draws 

 * ' Veterinary Physiology,' 1907 edition, p. 177. 



