10 FOOD INGESTION AND ENERGY TRANSFORMATIONS. 



PREVIOUS INVESTIGATIONS ON METABOLISM AFTER FOOD. 



Lavoisier and Seguin, 1789. The fact that the ingestion of food 

 causes an increase in the metabolism in the body was first made known 

 through the classical researches of Lavoisier and Se'guin. 1 As with 

 many phases of physiological chemistry, our first information as to 

 quantitative values for these important body processes is obtained 

 from the remarkable series of experiments carried out by Lavoisier. 

 Judging from incomplete statements appearing intermittently in the 

 writings of Lavoisier and of Se'guin, together with the drawings attrib- 

 uted to Madame Lavoisier, the expired air was collected by means of 

 an air-tight mask attached to the subject's face. It is of interest to 

 note that this method is now the basis of practically all of the modern 

 mine-rescue apparatus and " gas-masks", and is also finding extensive 

 use in clinical laboratories. 



The statement is made by Lavoisier that a man fasting, or at least 

 with an empty stomach and quiet, consumes in one hour 1,210 cubic 

 pouces of oxygen. This corresponds, according to the table of reduc- 

 tions of Gavarret, 2 to 24.002 liters. Lavoisier also states that during 

 digestion the oxygen consumption increases to 1,800 or 1,900 cubic 

 pouces, the latter value corresponding to 37.689 liters. Thus we note 

 an increment of approximately 700 cubic pouces due to taking food or, 

 in other words, somewhat over 50 per cent. The kind of food and the 

 amount eaten were not given. Lavoisier recognized the fact that 

 individuality may play a role here; we cite his criticism: 



"Nous ne parlons en ce moment que de rapports. On congoit, en effet, 

 que la consommation absolue doit varier conside"rablement dans diffe"rents indi- 

 vidus, suivant leur age, leur 6tat de vigueur et de sant6, suivant qu'ils ont plus 

 ou moins contracte 1'habitude des travaux penibles; mais il n'est pas moins 

 vrai qu'il existe pour chaque personne une loi qui ne se de'ment pas, lorsque 

 les experiences sont faites dans les memes circonstances et a des intervalles 

 de temps peu e'loigne's." 3 



In studying the literature 130 years after the appearance of Lavoi- 

 sier's first paper, it is surprising to note his clear conceptions of the 

 problems involved both in the muscular work of man and in diges- 

 tion. While an increment in metabolism amounting approximately 

 to over 50 per cent is somewhat higher than that commonly observed 

 and somewhat higher, in all probability, than modern methods would 

 show for the diet of the subject, nevertheless it is by no means an 

 impossibility. We have thus this earliest recorded estimate of the 

 increased energy required to digest a meal. 



'Seguin and Lavoisier, Meraoires de 1'Acad. des Sciences, 1789, p. 185; also Oeuvresde Lavoisier. 



1862, 2, p. 688. 



*Gavarret, Physique medicale. De la chaleur produite par les etres vivants. 1S55, p. 330. 

 3 S6guin and Lavoisier, Oeuvres de Lavoisier, 1862, 2, p. 69ft. 



