408 THEORIES OF J. MAYOW. [BOOK I. 



other salino-sulphureous particles secreted from the mass of the blood, 

 and by union with these cause an effervescing which produces muscular 

 motion. How the nitro-aerial or igneo-aerial particles reached the 

 muscles, Mayow did not feel quite certain. He was sometimes inclined 

 to think that they proceeded directly to the muscles from the blood ; but 

 it appeared more probable on further reflection, that the salino-sulphur- 

 eous or motive particles alone were supplied directly by the blood; while 

 the nitro-aerial particles approached the muscles through the brain and 

 nerves, being the same, in short, as the animal spirits. Why, asked 

 Mayow, should not the animal spirits be derived from the air rather 

 than from the food ? Indeed, it seemed to him impossible that the 

 immense waste of animal spirits could be supplied from any other 

 source. The salino-sulphureous or combustible nature of the motive 

 particles was thought to be shewn by this, that in violent exercise no 

 small loss of fat occurs, and if exercise is long continued fat almost 

 disappears : on the contrary, animals leading an easy inactive life grow 

 fat, and fat appears in large quantity in the muscles. A supply both 

 of igneo-aerial and of salino-sulphureous particles is indispensable to 

 continued animal motion. As movement is increased and more of 

 each sort of particles is wasted, more of them must be added to the 

 body. Not only must respiration be enlarged, but more food contain- 

 ing salino-sulphureous parts must be taken. Hence those substances 

 which contain much volatile salts and sulphur (i.e. combustible matter) 

 are best fitted to recruit the frame worn out by protracted labour. 

 Finally, Mayow clearly recognized that the animal heat arises, not solely 

 in the union of nitro-aerial and combustible particles in the blood 

 generally, but in that special union which is accomplished in muscles 

 during muscular contraction : part of the heat of an animal in violent 

 exertion arises in the union of nitro-aerial and salino-sulphureous par- 

 ticles in muscle 1 . 



This was in 1674. When we remember that it was nearly two 

 hundred years before physiological science fully overtook the specula- 

 tions of Mayow, that, although oxygen was discovered in 1774, it 

 was not until 1861 that Moritz Traube definitely announced that 

 muscular contraction depends upon the combustion of non-nitrogenous 

 matters in muscles themselves we shall feel no surprise that Mayow's 

 work was so speedily forgotten. Scientific judgment must have 

 been strangely uneducated to have allowed the experimenters of 

 that day to read and lose sight of observations which seem to 

 us now so exact and suggestive. It has been the fate of Mayow, 

 which his genius little merited, instead of leading science, to be twice 

 revived by antiquarian zeal, at the very moment when his dis- 

 coveries had been made over again by independent observers. After 

 the researches of Priestley, Scheele and Lavoisier had made brilliant 



1 Op. cit., part i., de sal-nitro etspiritu nitro-aereo, p. 152. "Quanquam calor iste in 

 animalibus, per exercitia violenta excitatus, etiam ab effervescentia particularum nitro- 

 aerearum et salino sulphurearum in partibus motricibus ort&, partim provenit, ut alibi 

 ostendetur. 



