PRACTICE DISSECTIONS 349 



mal '! Does the action of the drug on the bronchioles in 

 this experiment indicate any way in which the drug might 

 affect the normal respiration aside from its direct action 

 on the respiratory center? Do you know of any disease in 

 which the lungs mat/ be affected in a manner similar to 

 that brought about by eserine? Do you know of any 

 remedy that might be used to counteract each condition! 

 How might the remedy be applied? Stop the artificial 

 respiration and kill the animal. 



2. After death (if you have used a dog) shave the hair 

 off of an area about three inches long and three inches wide 

 over the lower part of the dorsal region of the spine. With 

 a scalpel make a small incision in the skin about one-half 

 inch to one side of the mid-line of the spinal column. A 

 small trocar or a long syringe needle (or even a knitting 

 needle) is now passed into the spinal canal, the needle or 

 trocar being directed inward, mesially and slightly toward 

 the head. By consulting a text-book on anatomy the stu- 

 dent can determine about what relation the point of inser- 

 tion of the needle through the skin should bear to the lower 

 end of the nearest spinous process. See if you can get 

 some spinal fluid to run out of the needle after it is in- 

 serted. Two or three punctures may be made for practice. 

 The needle is then left in position and the tissues are dis- 

 sected away around the needle down to the vertebrae and 

 the position and relations of the needle are carefully 

 studied. If you failed to pass the needle into the spinal 

 canal what was the cause? Could you now succeed in a 

 living animal! Sketch in your note book the relations of 

 the spinous processes to the openings into the spinal canal 

 and save for reference. Examine the size, structure and 

 relations of the spinal cord. Can you isolate the posterior 

 and anterior roots and the spinal ganglia? What are the 

 functions of these structures? 



