The pupil may also identify the following structures if a specimen is available which has the blood vessels injected.

Conus arteriosus, or "arterial trunk," a large artery passing obliquely forward from the ventricle, and dividing into three branches on each side. Carotid arteries, the first branches of the conus, to the head and neck. Aortas, the second branches of the conus, to the dorsal region. Pulmocutaneous arteries, the third branches of the conus, to the lungs and skin. Dorsal aorta, the large artery along the back, formed by the union of the two aortas. Iliac, or femoral arteries, the two posterior divisions of the dorsal aorta, supplying the legs. Posterior (ascending) vena cava, a large vein close to the dorsal aorta, passing forward from the kidneys. Hepatic veins, large veins connecting the liver with the posterior vena cava. Anterior (descending) venæ cavæ, large veins formed by the junction of the veins from the arm, neck, and head on the right and left sides. Subclavian veins, from the arms. Jugular veins, from the neck.

Questions.
  1. Of how many chambers does the frog's heart consist? Name them, and describe them as to size, color, and structure.
  2. Which chamber receives blood from the body, and which receives blood from the lungs?
  3. Name the large arteries and give the regions which they supply. Name the large veins and give the regions from which they come.
  4. Describe the lungs as to size, both when inflated and when uninflated. Describe their color; entirety or subdivision; texture.
  5. In the inflated lung, notice the interior partitions or chambers, which are called vesicles. How do they affect the amount of surface exposed for gas exchange in breathing?
  6. Measuring the lung collapsed and again when inflated, calculate its approximate volume in each case and state how much air it may take in during an inspiration.
  7. Describe the diaphragm and state its probable use as a factor in respiration or as a partition.
Advanced questions.
  1. Apparently the pure and the impure blood must commingle upon entering the single ventricle, but by a simple device this scarcely occurs. How would such commingling affect the purity of the blood as it reached the tissues, and hence affect waste removal, oxidation, body temperature, activity, and intelligence?
  2. What are the chambers of the fish's heart? of the mammalian (human) heart? How may the heart of the frog be regarded as intermediate between these others? How and where might the growth of a partition within it bring about the higher structure? (This actually occurs in certain reptiles.)
  3. The lungs are said to be outgrowths of the alimentary canal. Explain how their connection would tend to show this.

Suggested drawings.
  1. The heart and lungs in their normal position.
  2. The circulatory system, as seen in the injected specimen.
  3. A copy of the diagram or model of the circulatory system.
  4. A diagram of the respiratory tract from the nostrils to the lungs, by arrows showing the course of the air.