103 



aitical value of Ling and Gerard. If the dose given was insuffi- 

 cient to decrease the potential to this value the animal survives 

 and shows no symptom whatsoever. 



According to our assumptions £* is involved in various cellular 

 activities; so the symptoms in the whole animal, caused by the in- 

 gestion of toxic doses of a substance such as an aromatic nitro 

 compound which interferes with £*, can be expected to depend 

 on the question to which tissue or cell constitutent the drug has 

 the greatest affinity. According to the experience quoted, dinitro- 

 naphthol seems to have a special affinity for the cell membrane. 

 Dinitrophenol seems to have a greater affinity for mitochondria 

 and so its interference with cellular metabolism dominates the 

 picture. Toxic doses may kill the animal in hyperthermia, while 

 smaller and repeated doses produce emaciation. 



Substitution of acidic radicals in aromatic compounds is knov.n 

 to interfere with biological activity while leaving optical properties 

 untouched. Possibly, the acidic radical interferes with permeability, 

 slowing down the penetration into the cell. According, it was 

 found that dinitronaphtholsulfonic acid caused no acute symptoms 

 in the animal when ingested in the same doses as the free nitro- 

 naphthol, and caused no contracture of isolated muscle though it 

 quenched the phosphorescence in vitro with the same intensity as 

 dinitronaphthol. All the same, its biological activity was found to 

 be proportional to its in vitro action on £*, and equal to that of 

 free dinitrophenol: it killed the animal in the same doses but did 

 so with unspecific symptoms in a few days time, following a wast- 

 ing away of the animal. 



