(5) Nine air sacs cool the pigeon, give it buoyance, and mechanically aid the pigeon to breathe.
b. Digestive system. (1) Mouth is the opening through which food is received.
(2) Esophagus conducts food to the crop.
(3) Crop, or ingluvius, stores and softens the food.
(4) True stomach, or proventriculus, furnishes gastric digestive juices that digest proteins and carbohydrates.
(5) Gizzard is the grinding and mixing organ.
(6) Pancreas furnishes digestive juices that digest fats, proteins, and carbohydrates, besides furnishing certain internal secretions.
(7) Liver produces bile which helps digest food.
Figure 40. Loft cleaning equipment.