NERVES AND THEIR CONTROL 



PROBLEM LV 



A study of the nervous system, reactions to stimuli, and 

 habit formation. 



a. Anatomy 



Materials. Frogs preserved in alcohol or formalin, scissors, 

 forceps, hand lens, charts showing nervous system of man. 

 (Optionally use prepared specimens of the nervous system of 

 frogs or of mammals.) 



Note. The nervous system of man and animals is primarily 

 a device for making locomotion safe. 



Observations. 1. Open the abdomen of a frog and remove 

 the organs found in it. Find some white cords (nerves) near 

 the back. 



2. Trace some nerves into the legs, dissecting away the 

 muscle. 



3. Carefully remove the upper half of skull, and find some 

 white lobes (brain). 



4. Cut away the skin, muscles, and upper half of the back- 

 bone, so as to trace a large nerve in it (spinal cord). 



5. Refer to a chart showing nervous system of a frog, and 

 notice the branching. 



Conclusion. Compare the nerve cords with a telegraph sys- 

 tem. What corresponds to headquarters ? (Study the func- 

 tion of the brain in any good text.) 



Observations. 1. Note the white elongated hemispheres of 

 the forebrain, or cerebrum. The two anterior projections of 

 the cerebrum are called olfactory lobes. Where do these lobes 

 seem to lead ? W r hat is the meaning of the term 'olfactory ' ? 



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