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Dr. Paul Ehrlich. 



importance. In glancing through the modern text-books of pharma- 

 cology, mth rare exceptions, as, e.g., Stokvis, one finds absolutely no 

 mention of the distribution of drugs in the organism, a matter which 

 is of so much moment for arriving at a true comprehension of the 

 relations existing between pharmacological action, location in the 

 organism, and chemical constitution. As a matter of fact, the 

 methods for obtaining any knowledge of the exact distribution of 

 drugs in the body are as yet yqvj imperfect. Even if we can prove 

 that certain alkaloids are again recognisable as being, e.g., present in 

 .the brain, we are but little further advanced in our knowledge of 

 the process, because we cannot determine in which cells and which 

 system of fibres the alkaloid is localised. 



I may say, indeed, that as yet the investigation of the laws pertain- 

 ing to the minute distribution of a chemical substance in the body is 

 only possible when, as in the case of coloured bodies, these are at once 

 recognisable by the eye. But that it is possible at once to draw con- 

 clusions of therapeutic importance from the laws governing the distri- 

 bution was shown in the case of methylene-blue, in which I was able, 

 knowing its distribution in the body, to anticipate for it certain anti- 

 neuralgic and antimalarial properties which were both established by 

 subsequent investigation. It may be permitted me to call to mind, 

 that in malaria methylene-blue is especially of service in the case 

 of persons who, on account of susceptibility, cannot be treated with 

 quinine, and that in the hands of Koch it has shown itself of eminent 

 value in hsemoglobinuric fever, since as opposed to quinine it exercises 

 no destructive action on the erythrocytes. If we are not able to dis- 

 cover the principles governing the localisation of common chemical 

 bodies, which can be used in suitable quantities in chemical purity, 

 and which chemical and other reactions render perceptible, it was a 

 piori very unlikely that efforts directed to locating the toxines, which 

 are potent in the slightest traces, and which are bodies we have no 

 means of rendering perceptible to our senses, would be anything else 

 than absolutely without result. 



But that this is not so, has been shown by experiments carried out by 

 Professor Donitz, in the Steglitz Institute, to which, on account of their 

 great importance, I shall refer somewhat extensively. '\Mien a rabbit 

 receives a suitable dose of diphtheria or tetanus toxine injected directly 

 into the circulation, the animal remains for many hours well, and 

 then begins to show symptoms of illness, which gradually increase till 

 they end in death. In order to arrive at an explanation gf the incu- 

 bation period, Donitz determined the amount of antitoxine which, 

 injected intravenously immediately after the toxine, absolutely neu- 

 tralised the latter. This neutralising dose is able to render all the 

 toxine circulating in the blood innocuous. "When, however, the 

 neutralising dose so determined was injected not immediately, but 



