This is a diagram of the digestive tract. Notice how the food is submitted to the action of alkaline, acid, and then alkaline fluids.
Steele, Joel Dorman Hygienic Physiology (New York, NY: A. S. Barnes & Company, 1888)
1660×2400, 584.2 KiB
708×1024, 99.9 KiB
442×640, 50.7 KiB
221×320, 16.3 KiB