178 The English School [lect. 



refutes Borelli's arguments ; apparently he remained by his old 

 opinion until his death. 



Borelli sums up his exposition of the erroneous views put 

 forward concerning the purpose of breathing as follows : 



"It is clear from what has been said that the use of 

 " breathing is not the cooling of the excessive heat of the heart, 

 " nor the ventilation of the vital flame, nor the mixture of the 

 "heterogeneous parts of the blood brought about by the 

 " pressure of the inflated vesicles of the lungs, nor merely the 

 " passage of blood from the right to the left ventricle of the 

 " heart in order that the circulation may be carried on. But so 

 "great a machinery of vessels and organs of the lungs must 

 " have been instituted for some grand purpose ; and that we 

 " will try to expound, if possible, though we shall stammer as 

 "we go along." 



He remarks that, in spite of the experiment tliat air blown 

 through a tube into the bronchial tubes does not enter the 

 pulmonary vein, many authors maintain, and justly maintain, 

 that air does somehow find its way from the lungs into the 

 blood. These authors suppose for this purpose the existence of 

 minute pores leading from the interior of the lungs into the 

 blood vessels. Such a supposition, however, is, in his opinion, 

 not necessary, since air dissolved in liquids can pass through 

 membranes, and there is always in the bronchial passages some 

 fluid in which the air might be dissolved. 



He goes on to insist that "air taken in by breathing is 

 the chief cause of the life of animals," far more essential than 

 the working of the heart and the circulation of the blood. 

 A frog will live after its heart has been wholly cut away, and 

 insects may be divided into pieces and yet live for a while. 

 The stoppage of breathing, on the other hand, brings about in 

 all cases the cessation of life. 



" The experiment which proves most completely the truth 

 " of the assertion (that air is necessary to life) is the sudden 

 " removal of air by Boyle's pneumatic machine, or better still 

 "by the Torricellian vacuum with the help of mercury. 

 " Animals of all kinds shut up in such a vacuum immediately 

 " fall down dead ; but if the air be instantly renewed with 

 "care, may be brought to life again." 



