2GG A. I. RINGER AXI3 EMIL J. BAITMANS :.. 



We must picture these changes more from the dynamic point of view 

 than from the static. We must realize that in every cell'of the body the 

 protoplasm is in constant motion. It is a system where hundreds of chem- 

 ical reactions are going on continuously and almost simultaneously, where 

 molecules are flying hither and thither, some undergoing oxidation, others 

 undergoing reduction, and the whole struggling to reach an equilibrium. 

 This struggle for chemical equilibrium constitutes the life of the cell. 

 It is important also to bear in mind that the substances formulated in 

 the chart do not normally represent products of intermediary metabolism, 

 but rather stages or stations along a certain route of decomposition. ' The 

 reaction does not stop at any of these points for any length of time to allow 

 an accumulation of the products, except under abnormal conditions. For 

 example, when the supply of oxygen is insufficient the process may halt at 

 the lactic acid stage, then lactic acid can be detected in quantity. Just 

 as an express train operating between New York and Chicago cannot 

 arrive at its destination suddenly, but must go through certain stations 

 alcng the route, so glucose must pass certain intermediary stages before 

 reaching carbon dioxid and water. If the power does not hold out, natur- 

 ally there will be a forced stop at one of the stations. 



When we view the reactions on the chart we must also realize that there 

 are two forc.es operative, one which drives the reaction downward and an- 

 other which drives it backward to glucose. We are inclined to attribute 

 them to the action of ferments. But ferments are blind forces that do not 

 determine the direction of the reaction. Whether it goes to one side or 

 another is controlled by physical chemical factors such as the mass action 

 or relative concentration of the components. When the glucose concentra- 

 tion is high, the reaction swings in two directions with relatively great 

 force and speed. Glucose is rapidly converted to glycogen on the one 

 hand and to glyceric aldehyde on the other. 



Glycogenz;GLUCOSE^Glyceric aldehyde 



But the reactions from glycogen to glucose and from glyceric aldehyde to 

 glucose cannot be considered stopped. They probably go on at the same 

 time, but the former reactions overshadow the latter e Similarly if gly- 

 ceric aldehyde is fed to an animal we may picture the reaction in both di- 

 rections, but. going primarily in the line of least resistance. 



. . . ^-^JDioxyacetone 



Glucosel^GLYCERIC ALDEHYDE^ 



^-Pyruvic aldehyde 

 And so on with the other reactions. 



On the basis of these last considerations one may find an explanation 

 for the formation of glucose from practically all the intermediary metabo- 

 lites of glucose when administered to diabetic animals. When one gives 

 anv of these substances to a normal animal the reaction of that substance 



