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._ 8. 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? 9. 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.) 10. The lungs are said to be outgrowths of the alimentary canal. Explain how their connection would tend to show this. _Suggested drawings._ a. The heart and lungs in their normal position. b. The circulatory system, as seen in the injected specimen. c. A copy of the diagram or model of the circulatory system. d. A diagram of the respiratory tract from the nostrils to the lungs, by arrows showing the course of the air. The Nervous System of the Frog _Materials._ Specimens which have the brain exposed and other specimens whose viscera have been removed so that the spinal nerves can be seen; pans or shallow dishes of water and forceps. _Observations._ The nerve tissues are generally white in color unless they have been specially treated and stained. The pupil should identify the following structures:-- _A. Brain_, those enlargements of nerve tissue situated in the head and composed of four principal parts, as follows:-- 1. _Cerebral hemispheres_, a pair of elongated lobes, the anterior enlargements. 2. _Mid brain_, or _optic lobes_, a pair of large ovoid structures, projecting diagonally forward and sidewise. 3. _Cerebellum_, a slender, transverse ridge, close behind the midbrain. 4. _Medulla_, the anterior end of the spinal cord, widest in front and containing a triangular depression. (Frequently a pair of smaller enlargements is to be seen in front of the cerebral hemispheres; they are the _olfactory lobes_, and from them nerves pass forward to the nasal chamber.)