258 Mayow 



the fermentation and the motion of the blood are 

 caused by nitro-aerial particles. And this has also 

 been noted by the learned Dr Thruston. Where- 

 fore, for the proper fermentation and fluidity of the 

 mass of the blood there is need of a more frequent and 

 a fuller respiration, even for some time after violent 

 movement. And from these things we may seek the 

 reason why the blood drawn during convulsive 

 paroxysms is usually very thick and somewhat 

 grumous. For in more violent muscular contraction 

 there is very great expenditure not only of nitro-aerial 

 but also of saline-sulphureous particles (as it is on their 

 mutual action that the fermentation and fluidity of the 

 blood depend), and therefore the mass of the blood 

 must to some small .extent be coagulated. But this 

 is especially the case when the parts which serve for 

 respiration suffer convulsion ; for then, on account of 

 the nearly suppressed respiration, the loss of nitro- 

 aerial particles caused by the convulsive movements 

 is not, as in other cases of violent movements, repaired 

 by respiration. 



One might at first sight object to what has been 

 said above, that the animal spirits form a chief part 

 of the body, and that it is therefore likely that they 

 should be derived not from the air, as being something 

 external and foreign to the body, but rather from the 

 nobler particles of the blood, when these have been 

 brought to the highest subtlety and vigour : further, 

 that it does not become the admirable artifice of the 

 animal mechanism that it should be set in motion by 

 an external principle. I reply that, of whatever sort 

 the animal spirits may be, they must certainly be 

 supplied from without. For that they should be 

 formed from the blood, as the mass of the blood is 

 daily renewed from food, spirits even arising from 



