July 7, 1905.] 



SCIENCE. 



11 



As regards fat metabolism Geelmnyden^^ 

 is inclined to the opinion that oxybutyric 

 acid, aceto-acetic acid and acetone are nor- 

 mal metabolism products derived from 

 members higher up in the series. 



As regards dextrose Stoklasa^° announces 

 that all animal and vegetable cells contain 

 enzymes capable of converting dextrose 

 into alcohol and carbon dioxide. He-^ also 

 finds a ferment in animal tissues able to 

 convert sugar into lactic acid. He quotes 

 Oppenheimer's experiment, showing that 

 whereas fresh normal blood yielded little 

 lactic acid on standing at 37° C, much 

 greater amounts were formed if dextrose 

 was added. He believes that this lactic 

 acid is subsequently converted into alcohol 

 and carbon dioxide. 



Embden-^ comes to the conclusion that 

 blood sugar perfused through the liver may 

 be broken up into lactic acid. It has been 

 previously shown that lactic acid could be 

 converted into dextrose and it is a curious 

 fact that this same dextrose may pass 

 through the lactic-acid stage on its way to 

 oxidation. 



A. R. Mandel-^ in the writer's laboratory 

 has show^n that lactic acid disappears from 

 the blood and urine in phosphorus poison- 

 ing if diabetes be induced. Here the 

 mother substance of the accumulating lactic 

 acid is removed in the urine. Any con- 

 siderable production of alcohol in tissue 

 metabolism, while possible, does not seem 

 probable in light of the known physiolog- 

 ical action of the substance. 



^^ Geelmiiyden, Zeitschrift fur physiologische 

 Chem.., 1904, Bd. 41, p. 128. 



-° Stoklasa, Centralhlatt fur Physiologie, 1903, 

 Bd. 17, p. 465. 



-^ Stoklasa, Jelinck und Cerny, Centralhlatt fur 

 Physiologie, 1903, Bd. 16, p. 712. 



-- Embden, ' Verhandlungeii der 6sten Interna- 

 tionalen physiologen Congress,' Centralhlatt fur 

 Physiologie, 1905, Bd. 18, p. 832. 



-^ Mandel, ' Proceedings of the Am. Physiol. So- 

 ciety,' American Journal of Physiology, 1905, Vol. 

 13, p. xvi. 



Rubner-^ gives the following theory of 

 metabolism : Living proteid, through the 

 vibrations of its particles, metabolizes the 

 food substances. The action resembles 

 catalysis. The energy liberated reacts on 

 the particles of protoplasm, causing a 

 change in their position and a cessation of 

 metabolism. The particles then return to 

 their original position and the cycle begins 

 again. These processes require a fixed 

 amount of energy. Rubner does not give 

 his reasons for believing in this rhythm of 

 excitation and rest. 



The quantity of the combustion depends 

 on the power of the cells to metabolize 

 (Voit). In the resting state this metabolic 

 power of the cells is influenced by the 'law 

 of skin area' (Rubner). Temperature 

 (cooling or warming) and nerve excitation 

 (muscle work, chemical regulation) affect 

 the power of the cells to metabolize, per- 

 haps through an increase in the oscillation 

 of the particles, an effect w^hich is in turn 

 maintained at the expense of the energy 

 derived from metabolism. Living proto- 

 plasm metabolizes in accord with its neces- 

 sities at the time, and never more. Large 

 quantities of nutrient materials furnished 

 will not increase cell metabolism. If food 

 be ingested above the requirement for the 

 organism, any excess will be retained in the 

 body. The kind of metabolism depends 

 upon the constitution of the fluid feeding 

 the cells, and whether proteid, carbohy- 

 drates or fats have been ingested. 



Each ingested foodstuff exerts a specific 

 dynamic action (Rubner). At a tempera- 

 ture of 33° C. the ingestion of the starva- 

 tion requirement of energy in the form 

 of fat increases the requirement for energy 

 ten per cent., carbohydrates raises it five per 

 cent., proteids thirty per cent. In other 

 words, in the case of meat, in order to ob- 

 tain calorific equilibrium about 140 calories 



-^ Rubner, ' Von Leyden's Handbuch der Ernah- 

 ungstherapic,' 1903, p. 78. 



