202 Mayow 



supposed, drawn upwards when contracted by 

 repeated irritations. For in systole and in its con- 

 traction, it is drawn downwards, as shown above, and 

 so causes inspiration rather than that expiration 

 which takes place in laughter. From what has been 

 said it is evident that risibility is peculiar to man not 

 because the nerve of the diaphragm communicates in 

 man, but not in beasts, with the cervical plexus, and 

 by means of it with the brain — an opinion which the 

 learned Dr Willis has maintained in his book on the 

 Anatomy of the Brain. For laughter does not take 

 place because the diaphragm, on account of an 

 instigation brought by the said nerve from the brain, 

 contracts violently with repeated throbs and com- 

 presses the lungs, as this learned man supposed. For 

 it has been shown that laughter does not proceed 

 from the action or systole of the diaphragm, but, on 

 the contrary, from its diastole. 



We have spoken thus far of the manner in which 

 respiration takes place, and it now remains for us to 

 inquire into its use. This is indeed a most difficult 

 affair, for there is not more accord as to its necessity 

 than doubt as to its use. 



For not only is air inspired useful for tasting and 

 smelling, and expelled, for talking, shouting, cough- 

 ing, sneezing, and spitting, and again, when retained, 

 for the expulsion of urine and faeces, for parturition, 

 and for moving on the chyle, the lymph, and the 

 blood ; the breath we inspire is destined for a still 

 nobler use : from which arises such a necessity of 

 drawing breath that we cannot indeed live a moment 

 without it. 



Some suppose that respiration chiefly serves for 

 cooling the heart ; but heating rather than such a 

 cooling seems to suit the circulation and fermentation 



