16 VETEKINAEY TOXICOLOGY 



great part, depending on the quantity, may be held back 

 from the blood stream. The activity of the liver in this 

 respect appears to be proportional to its glycogen content, 

 for when this is reduced the liver no longer arrests the drug, 

 and a very much smaller dose than the normal may be toxic. 

 Some substances — e.g., salts of sodium and potassium, 

 alcohol, and digitalis — are not arrested by the liver. Metals 

 are stored in an unknown condition, possibly as albuminates, 

 in the liver, and many unstable poisons are modified ; e.g., 

 ammonia is converted into urea, and some alkaloids 

 oxidised, so that the liver does not exercise a merely 

 passive function in its protective capacity. The condition 

 as to health or disease of this organ is thus of importance, 

 since when the glycogenic function is low, little arrest of a 

 poison will occur. It is chiefly in the liver that accumula- 

 tion takes place. Besides metals a few organic poisons, 

 notably digitalin, helleborein, and strychnine, are cumula- 

 tive, although not necessarily stored in the liver. To desig- 

 nate a poison as cumulative does not endow it with 

 exceptional properties. The only difference between such 

 and ordinary drugs is, that elimination is slower in the 

 former than in the latter, though both may be stored. The 

 difference is of degree, not kind, although important from 

 the practical standpoint. The sudden display of symptoms, 

 after more or less prolonged dosage, means, then, that elimi- 

 nation has not kept pace with absorption, or that absorption 

 has, through some cause become more active, or elimination 

 less so. 



Elimination. — Poisons may be divided roughly into those 

 which are slowly (cumulative) and those which are rapidly 

 eliminated. ! In the first category we have, as the most impor- 

 tant examples, the metals, which are arrested chiefly by the 

 liver. Prom that organ they pass off in part by the blood, 

 but mostly by the bile. From the bile a portion may pass 

 into the faeces, and a portion be reabsorbed and carried 

 back to the liver, thus establishing a gastro-hepatic circula- 

 tion (Claude Bernard). 



Most of the poisons, however, do not accumulate, and 



