214 
FR. BLAZEKOVIC. 
counteract tlic diminution of the cavities of the heart, if it were 
not overcome by the contraction of the muscles of the heart. 
The thoracic aspiration influences therefore only the expansion 
and more strongly during inspiration than during expiration— 
during diastole—and results in filling the whole heart with blood 
during the short pause of relaxation. By the negative pressure, 
which the elasticity of the lungs exercises over the relaxed auricle, 
the lungs are filled during diastole more strongly with blood. 
The reflux of the blood is prevented by the closing of the valve of 
the auriculo-ventricular opening. Toward the end of the diastole 
of the auricule the chambers relax, the valves open, and in the 
moment of pause in which the four cavities of the heart are re¬ 
laxed, the blood flows out of the auricle into the ventricle. By 
this means the auricle, notwithstanding the small space during the 
following diastole, can wholly fill the ventricle with blood. The 
lumen of the auricle becomes smaller during systole. Under the 
pressure of the contracted walls of the auricle the blood obtains its 
impulse to flow off into the existing opening; the ventricle being 
at the same time in diastole the blood can flow out of the auricle 
without restraint until a stronger filling of the auricle obstructs a 
further influx of the blood. The replenishing of the ventricle is 
assisted by the thoracic aspiration. The auriculo-ventricular 
valves cannot hinder the progress of blood into the ventricle, 
because during the diastole of the ventricle they form a funnel 
open above and below. The tubercle of Lower, which contracts 
simultaneously, acts at the same time as a dam and prevents stag¬ 
nation of blood which might take place, in the vena cava, dis¬ 
charging nearly in the opposite direction. The flow of blood to¬ 
ward the auriculo-ventricular opening is predominant, because the 
contraction begins at the mouth of the veins and spreads over the 
whole lumen of the auricle. Still stagnation of the blood may 
happen during systole of the ventricle for, with the exception of 
the tliebesii, other valve contrivances are lacking. They are, how¬ 
ever, limited to a certain degree, for the strong muscular fibres, 
which, girdle like, encircle the end pieces of the vena cava, contract 
at the beginning of the systole of the auricle, lessen the opening 
of the vein and thereby render a stagnation more difficult. The 
