110 



THE CARDIO-PNEUMATIC MOVEMENT. 



air must be drawn into the chest when the heart contracts ; whenever 

 the heart relaxes, i.e., during diastole, air must be expelled through the 

 open glottis. But we must also take into account the degree to which 

 the larger intrathoracic vessels are filled with blood. These movements 

 of the air within the lungs, although slight, seem to be of importance 

 in hybernating animals. In -animals in this condition, the agitation of 

 the gases in the lungs favours the exchange of C0 2 and in the lungs, 

 and this slow current of air is sufficient to aerate the blood passing 

 through the lungs. [Ceradini called the diminution of the volume of 

 the entire heart which occurs during systole meiocardie, and the 

 subsequent increase of volume when the heart is distended to its 

 maximum, auxocardie.] 



Method. The cardo-pneumatic movements i.e., the movement of the respira- 

 tory gases dependent on the movements of the heart and great vessels may be 

 demonstrated in animals and man. A manometric flame may be used. Insert one 

 limb of a Y-tube into the opened trachea of an animal, while the other limb passes 

 to a small gas-jet, and connect the other tube with a gas-jet. It is clear that the 

 movements of the heart will affect the column of gas, and thus affect the flame. 

 Large animals previously curarised are best. It may also be done in man by 

 inserting the tube into one nostril, while the other nostril and the mouth are 

 closed. [A simpler and less irritating plan is to fill a wide curved glass-tube with 

 tobacco smoke, and insert one end of the tube into one nostril while the other nostril 

 and the mouth are closed. If the glottis be kept open, and respiration be stopped, 

 then the movements of the column of smoke within the tube are obvious.] 



Fig. 36. 



Landois' cardio-pneumograph, and the curves obtained therewith A and B, from 

 man, 1 and 2, correspond to the periods of the first and second heart-sounds; 

 C, from dog; D, method of using the apparatus. 



Cardio-Pneumograph. Ceradini employed a special instrument, while 

 Landois uses his cardio-pneumograph which consists of a tube (D), about one inch 



