210 SPECIAL PHYSIOLOGY 



as if to strike the subject in the face. Observe the winking of the 

 eyelids another protective reflex. 



(9) Let the subject again direct his vision toward a distant object; 

 gently touch the conjunctiva of the eyeball with the sterilized round 

 end of the glass rod. The convulsive winking is a protective reflex. 



(10) Let the subject sit near a window, and, looking through the 

 window, direct his vision toward some object not more than twenty 

 feet away. Suddenly shade the eyes of the subject for a few moments; 

 then remove the shade and observe the change in the size of the 

 pupil. During the experiment let the subject maintain the same 

 state of accommodation, if possible. 



(/) Cutaneous Reflexes. (11) Tickle the base sole of the foot. The 

 foot will be involuntarily withdrawn the plantar re-flex. 



(12) Pinch skin of neck. The pupil will dilate the ciliospinal 

 reflex. 



There are various other cutaneous reflexes, such as the cremas- 

 teric, abdominal, epigastric, scapular, and gluteal. 



(g) "Tendon Reflexes." These phenomena are not really reflexes, 

 though they have been called that for a very long time. They may 

 be studied in this connection. Let the student give reasons why the 

 responses to the stimuli are not necessarily reflexes. 



(13) Ankle Clonus. Let the subject's leg be supported as by 

 resting it across a chair, the subject being seated. Let the observer 

 place the hand upon the ball of the foot and press suddenly, so as 

 to put the tendo Achillis upon the stretch. There results a series 

 of clonic contractions. This phenomenon is not observed in a healthy 

 subject. 



(14) " Patellar Reflex" or Knee-jerk. Let the subject cross the 

 legs in a posture frequently assumed when sitting. Tap the tendon 

 below the patella with the edge of the hand, with the back of a thin 

 book, or with a percussion hammer. The quadriceps extensor muscle 

 will be suddenly stretched and will respond with a quick contrac- 

 tion, which will throw the foot forward in a kicking motion. This 

 phenomenon is present in health, and it may be modified in disease. 



III. THE ACTION OF STRYCHNINE UPON THE NERVOUS SYSTEM. 



1. Material. One dog; two frogs; sulphate of strychnine. 



2. Preparation. Make a solution of sulphate of strychnine, 0.01 

 grm. to 10 c.c.; also concentrated solution, 0.2 grm. to 10 c.c. pithed 

 frogs. Do not fasten the dog to the dog board. Set up electric 

 apparatus to obtain tetanizing current. 



3. Experiments and Observations. (1) Hypodermic injection 

 of 2 mg. strychnine per kg. of the dog. This dose is invariably lethal, 

 even with early antidotal treatment. 



