22 — 



movements consequently so much better executed, this animal makes 

 an excellent next step in the series. It may be studied in the same 

 manner as the salamander. Compare the two and see what in one al- 

 lows it to be so superior to the other in its movements. 



In the same way, study the motions of a lizard, a dog, a cat, a horse, 

 cow and man. Observe the motion of a bird in flying. A pigeon is 

 most easily obtained. Gulls may be w-atched as one crosses on the 

 ferries. 



Of the invertebrates, observe as many as can be obtained; tor example, 

 insects — beetle, grasshopper, butterfly, etc.; a slug or snail. 



Motions in general well observed, the class will be interested in seeing 

 the mechanism of motion. The leg of a frog, chicken or rabbit is each 

 excellent, but of course that of any small animal will answer. Any ob- 

 jections to dissecting an animal will not apply, or be raised by bringing 

 a leg only of one of these animals to class. 



Directions for examining the specimen: Slit the skin along the leg, 

 lay it back, but do not remove it. It should be seen just how the skin 

 fits to the leg; and besides, the specimen keeps in better condition if the 

 skin can be laid back over it when the specimen is not being used. 

 Separate carefully, without cutting any of them, or detaching them 

 from their connections, all the parts of the leg, muscles, tendons, 

 nerves and bloodvessels. 



Have the pupils see well the muscles, and their tendons, and how 

 they are attached to the bones. Pull on each muscle to see its action 

 and how it is accomplished. Have them see the nerves and how they 

 run into the muscles; the same with the bloodvessels. 



After these have been clearly made out by each member of the class, 

 have the muscles removed to see better the bones and the exact manner 

 in which they are held together. Then take apart a joint and see its 

 ligaments, the cartilage-capping of the bones, and the exact way in 

 which they fit and act upon one another. The facts of the structure of 

 a joint may be further pursued with larger joints of beef, sheep, or pigs, 

 obtained in the meat market. 



The foregoing may be made the subjects of many lessons. What has 

 been suggested may be much extended according to time and circum- 

 stances. For example, a general view of the whole muscular system 

 may be made by examination of the other parts of the animal. 



The Skeleton. 



Next the study of the skeleton may be taken up. The bones will by 

 this time be seen in their true light as levers for motion and points of 

 attachment from which muscles make their pulls; also as solid places on 

 which other bones rest in their action as levers — that is, 2.s fulcrums . 

 The work may now be with skeletons of representative vertebrates, and 

 wdth levers and their properties. 



