66 A MANUAL OF ZOOLOGY 



gland Into two branches, the cutanebus artery, and the pul- 

 monary artery. To what do they supply blood? "Make a 

 diagram of the arterial system. 



Heart — Cut off the blood vessels some distance from 

 the heart. Insert bristles of different color into the carotid 

 arch, the aortic arch, and the pulmonary arch. Pin the 

 heart down dorsal side up. Dissect under water, cutting 

 through the ventricle and other parts of the heart to 

 expoSe their cavity. Study the ventricle. What is the 

 thickness and texture of its walls? Compare with the 

 auricles and the truncus arteriosus. Is the ventricle di- 

 vided? Look for the auriculo-ventricular aperture on the 

 right of the specimen. Are there valves here? How many? 

 Name them. Notice their connection with the ventricles. 

 Notice the inter-auricular septum. What is its structure, 

 direction, and position with reference to the truncus arter- 

 iosus and the auriculo-ventricular aperture? Locate the 

 opening of the sinus venosus, in the right auricle, the 

 sinu-aurlcular aperture. Find the opening of the pulmo- 

 nary veins, close to the septum, near the top of the left 

 auricle. What relation does the truncus arteriosus have 

 with the ventricle? Notice the longitudinal valve in the 

 truncus. Notice the relation of the carotid, the aortic, and 

 the pulmonary arches of the truncus. Make a diagram of 

 the heart, and Its connections. On a live fi;og notice the 

 pcsterior lymph hearts on either side of the^urostyle. 

 Study the meaning of the lymphatic system, whffi; it con- 

 sists of, and what relation It has to the circulatory system. 

 Make a mount of frog's blood in normal salt solution. 

 Note the two kinds of corpuscles. How do they compare 

 in number? What is their shape? Run some^acetic acid 

 under the cover glass. What Is the effect? Make a mount 

 of human blood as above; compare the corpuscles In every 

 respect with those of the frog. Pith a frog and prepare 

 the web of his foot for the miproscope stage. Study the 

 circulation of the blood: Can you distinguish arteries, 

 capillaries, and veins? Study carefully with the high 

 powgf. If you have to use the mesentery, the corpuscles 

 and their Inovements. Are they all In closed vessels? 

 .What exceptions do you find? Make' a drawing represent- 

 ing the corpuscles of tlie frog and those of man. 



