Beneath the trachea note the long _œsophagus_. Inflate the œsophagus with a blowpipe and note how distensible is its lower end near the breast. This distensible portion is called the _crop_. If the alimentary canal be drawn out straight the œsophagus will be found to run as an almost straight tube down the left side of the body to the gizzard. This latter organ has very thick muscular walls and in it the food is ground up among the small bits of gravel it contains. Extending from the gizzard near the entrance of the œsophagus note the long _pyloric loop_ of the intestine called _duodenum_. Within this loop is a long pinkish gland, the _pancreas_, which empties by a duct into the duodenum. Into the duodenum also the overlying liver empties its secretion of bile from the median-placed _gall-bladder_. From the duodenum the _small intestine_ or _ileum_ extends with many convolutions to its exit through the cloacal aperture. On the intestine near the cloacal opening note a pair of glandular structures, the _cæca_. The short part of intestine between the cæca and cloaca is called the _rectum_. On the left side of the body beneath the gizzard note a dark glandular structure, the _spleen_. Make a drawing of the dissection as so far worked out. TECHNICAL NOTE.--Remove the alimentary canal, cutting it free posteriorly at the cæca and anteriorly just above the muscular gizzard. Cut open the gizzard and note its structure. The contained sand and gravel grains are picked up by the bird as it eats. On either side of the throat note the well-defined _thyroid gland_; in young sparrows will be noted on each side of the neck a mass of tissue, the remains of the _thymus gland_, which disappears in the adult. Cut transversely through the lower end of the heart and note that the ventricles are wholly distinct, whereas in the toad and snake they are incompletely separated. In the bird there is a complete double circulation. Its blood is not mixed, the pure with the impure, as in the toad and snake. Blood passing through the _right auricle_ and _ventricle_ goes to the lungs; on its return to the heart purified, it enters the _left auricle_ and _left ventricle_ thence to pass out over the body through the arteries.