360 COLLOIDS IN BIOLOGY AND MEDICINE 



In common parlance poisons are such substances as are harmful to 

 warm-blooded animals if they are taken by mouth or are inspired even 

 in minute quantities. With few exceptions "poisons," popularly 

 so-called, are acids, alkalis, various metallic poisons, CO and similar 

 substances, nerve poisons which even in minimal quantities may 

 depress essential functions, e.g., strychnine, atropine, etc. 



The actual poisonous effect, the death of the organism, is only the 

 closing act of a complicated drama which is enacted before our eyes. 

 The introductory scenes are for us no less important since they 

 teach us what phenomena may lead to a tragic termination. The 

 drama may end happily if the concentration of the drug is kept 

 sufficiently low or suitable antidotes are employed. From our point 

 of view it is impossible to separate Toxicology and Pharmacology. 



Next in importance to the concentration, the most important 

 influence upon toxicological or pharmacological action is the dis- 

 tribution. The fundamental and essentially chemical idea of distri- 

 bution was transferred by PAUL EHRLICH to the processes in 

 multicellular organisms. Minimal quantities of alkaloids have such 

 intense action because, in conformity with this view, they are con- 

 centrated in definite groups of nerves. In the treatment of infectious 

 diseases, it is necessary to find substances which will be so distrib- 

 uted between the infected organisms and the infection producers 

 that the largest possible quantity becomes attached to the micro- 

 organisms and the least possible is attached to the man, domestic 

 animal or plant. It is readily seen that the distribution may be 

 either a chemical combination, a distribution between two solvents 

 or a variety of adsorption. In but few cases has it been possible to 

 determine the kind of distribution adopted. H. FREUNDLICH has cal- 

 culated from the researches of W. STRAUB * that an adsorption equi- 

 librium obtains for the distribution of veratrine between the heart 

 muscle of a marine snail (aplysia limacina) and the bath containing 

 it. In- the special section we shall give other examples. 



To cause damage, the substance taken up must also change the 

 affected organ of the multicellular organism and under certain con- 

 ditions it may be immaterial whether the change is reversible or 

 irreversible. A poison which renders the respiratory muscles func- 

 tionless for only a few minutes as, for instance, curare, causes death 

 in warm-blooded animals, though the absorption is reversible. 

 Cold-blooded animals, for instance the frog, may, on the contrary, 

 live for days or even recover since they are able to breathe through 

 the skin. We must assume that the organs most essential to life 

 have special protection against many, especially autogenous toxins. 

 This may be a physical protection, in a partially isolating channel 



