56 PRACTICAL PHYSIOLOGY 



2. Sounds of the Heart. 



With the stethoscope provided, listen over the cardiac impulse 

 and over the second right costal cartilage. Put a finger on the 

 cardiac impulse and try to time the sounds heard in relationship to 

 this. Note the characters of the sounds. 



3. The Arterial Pulse (see p. 57). 



III.' Cardio-pneumatic Movements. Do the Movements of the Heart 

 cause Movements of the Air in the Air Passages ? 



Fill the mouth, nose and pharynx with tobacco or other smoke. 

 Hold the nostrils. Insert in the mouth the wide end of a wide bore 

 glass tube drawn to a somewhat fine point. Stop breathing and 

 keep the glottis open. Note any movement of the smoke in the 

 tube, and time it with the cardiac impulse. 



What conclusion do you draw as to the influence of the cardiac 

 cycle upon the movements of air in the air passages ? 



Lesson XII. To be provided for each pair of Students. 



1. Sheep's heart, fresh or preserved in formalin. 2. Dead frog, preserved in 

 formalin. 3. Cardiograph and recording drum. 4. Stethoscope. 5. Long 

 wide bore glass tube, drawn to fine opening. 



For the Class. 



Microscope with a low power and a specimen of a longitudinal section of 

 the heart of a mouse. Models of sections of the thorax. 



LESSON XIII 

 CIRCULATION IN THE BLOOD VESSELS. 



Examine the circulation in the web of the foot of a frog or in a 

 tadpole's tail under the microscope. Identify arterioles, capillaries 

 and veins and notice the character of the flow in each. 



I. Schema of Circulation. 



1. General Distribution of Pressure. 



Examine the schema of the blood vessels made of elastic tubes 

 provided, and identify the parts representing arteries, capillaries 

 and veins. Attach the arterial end to the water tap or to the nozzle 

 of a Higginson's syringe in a basin of water and fix vertically in 

 stands the two glass tubes connected with the arteries and veins 

 respectively. Cautiously turn on the water or gently pump by 

 means of the syringe and measure the pressure in the arteries and 

 in the veins, and calculate it in mm. of mercury. Note the effect 

 of (a) varying the force of inflow by turning off and on the tap or by 

 varying the force of the pumping, (6) varying the resistance to outflow 

 by constricting the arterial tubes. 



