88 DIGESTION AND RESORPTION 



experiments depends upon the circumstance that 

 they have considered the whole quantity secreted 

 to the stomach, whereas Khigine has observed 

 the quantity delivered by a " small stomach," which 

 is only a small fraction of that given to the chief 

 part of the stomach. 



London has carried out a great many experi- 

 ments regarding the quantity of undigested flesh 

 in a dog's stomach three hours after the food had 

 been given. The quantity of flesh given varied 

 between iooand iooo grammes. The dog's weight 

 was 25-2 kilogrammes. When I calculated these 

 figures, I observed that the whole progress of diges- 

 tion might be expressed by the following formula : 



dx\dt= 125(1 - e -o-oo6^ 



in which x is the quantity of undigested flesh in 

 grammes, dx : dt gives the quantity digested in 

 one hour. 



This formula is graphically represented in the 

 following diagram (Fig. 23). The uppermost curve 

 refers to the digestion of 1000 grammes flesh. The 

 curve for 800 grammes is obtained from that for 

 1000 grammes simply by transposing the zero-point 

 of time by i-6 hours, i.e. to the point where the 

 1000 grammes-curve cuts a horizontal line, jy = 8oo, 

 and so on for smaller quantities of food — in the dia- 

 gram the curves for 600, 400, 200 and 100 grammes 

 are drawn. The dotted curve is found with the same 

 dog some time later. Its digestive power was then 

 diminished in the proportion 1 :o-8, so that the 600 



