THE CIRCULATION OF THE BLOOD 95 



(3) Let the subject lie on his left side. Record results. 



(4) Let the subject sit. Record results. 



(5) Let the subject stand. Record results. 



(6) Let the subject take vigorous exercise for five minutes. Take 

 observations of pulse rate and pulse pressure while the subject stands. 



(7) From the tabulated results of the above observations write in 

 a list the postures and conditions which give an increasing series of 

 pulse pressures. 



(8) Prepare a similar list of the postures and conditions which 

 give an increasing series of pulse rates. 



(9) Are these two series alike in the order in which the conditions 

 are named? i. e., do the conditions which give high rate give also 

 high pressure? Account for what you discover. 



(10) If pulse rate increases, under what conditions could pulse 

 pressure fall (P=Hr X Hs X 



IX. TO DETERMINE THE INFLUENCE OF THE VAGUS NERVE 

 UPON THE ACTION OF THE HEART. 



1. Appliances. Operating case; a pair of curved, blunt-pointed 

 shears, or, better, a pair of barber's clippers; a rabbit board; a large 

 sheet of heavy paper; cotton; ether; thread; one dry cell; induc- 

 torium; shielded electrode (Fig. 54); seven wires; stethoscope; a 

 rabbit; contact key; short-circuiting key. 



FIG. 54 



A shielded electrode of hard rubber, bearing copper or platinum wires. 



2. Preparation. Let six or eight students be divided into three 

 or four groups of two each. 



Let the group " a" be responsible for the anaesthesia. Use the 

 sheet of heavy paper to make a conical hood, whose spiral turns may 

 be held in place with sealing-wax or pins. Place a wad of cotton 

 loosely in the mouth of the cone. 



Let the group "b" perform the operation. Tie the rabbit back 

 downward upon the holder; fix the nose in special holder; with the 

 barber's clippers remove the hair from the ventral side of the thorax 

 and neck; make hands and instruments clean; place instruments in 

 shallow basin of warm water; cut two or three ligatures of thread 

 and place them in the instrument basin. 



Let the group "c" arrange the electric apparatus for stimulation 



