METABOLISM IN NEUROMUSCULAR DISEASES 711 



that they attract oxygen to the tissues. Nencki and Sieber believed that 

 they could measure the oxidizing power of the body under different con- 

 ditions, by determining the amount of benzol that, can be oxidized in the 

 body to phenol ; and concluded, as a result of such experiments, that in 

 leukemia there is a decreased power of oxidation (Nencki and Sieber). 

 Lactic acid formation in animals, suffering from phosphorus poisoning, 

 has been attributed to decreased oxidation resulting from the low heart 

 rate. Insufficient oxygen supply has been held responsible for glycosuria 

 (Araki(fc)). 



Examples might be multiplied, but these will suffice to illustrate the 

 nature of the fallacy. 



The source of the error is found in the writings of Lavoisier. In 

 1777 (Lavoisier) Lavoisier cited metabolism experiments which he had 

 carried out on birds, to show that respiration results in a combination of 

 the carbon of the blood with oxygen to form carbon dioxid, from which he 

 concluded that the process is analogous to that which, two years previously, 

 he had described as combustion. But in elaborating this theory twelve 

 years later, he laid the foundation for future error (Seguin et Lavoisier 

 (a)). In this communication he speaks of incomplete oxidation of di- 

 gestive products as a possible cause of disease, and urges the use of 

 purgatives to rid the body of such products; he attributes the fevers of 

 hospitals and prisons to the insufficient oxidation resulting from the 

 impure air. In the following year, he declared that the metabolism is 

 more active, and, therefore, more heat is formed in cold climates because 

 the cold air is denser than warm air, and a greater amount of oxygen 

 per unit of volume comes in contact with the surface of the lung (Seguin 

 et Lavoisier(&)). 



But Lavoisier's writings contain also the germ of the truth. In his 

 communication of 1789, he states that, in spite of what should be ex- 

 pected, experiments with guinea pigs demonstrated that these animals 

 take up the same amount of oxygen, and give off the same amount of 

 carbon dioxid, whether they breathe pure oxygen or a mixture of oxygen 

 and nitrogen. Lavoisier was already, therefore, on the right track. By 

 1789, he had overcome the technical difficulties of constructing apparatus 

 for carrying out metabolism studies even in man; 2 by 1791, one of his 

 pupils, Seguin, had developed a method of measuring the amount of oxy- 

 gen in a mixture of gases (measuring how much of the gas would combine 

 with heated phosphorus) (Seguin) ; and another pupil, Hassenfratz, by 

 showing that the temperature in the kings is no higher than elsewhere in 

 the body, had corrected the erroneous notion that the oxidation takes place 

 in the lungs. It is highly probable, therefore, that Lavoisier might have 



2 In 1789 Lavoisier demonstrated this apparatus to the members of the Academy, 

 and in his communication described certain features of it; he promised to publish later 

 a detailed description. In 1790, he again promised to describe this apparatus. I have 

 searched for this promised report in probable places, but have never been able to find it. 



