On Muscular Motion and Animal Spirits 267 



sufficient abundance when required. I am not able 

 to decide certainly whether in terrestrial animals 

 also, besides the nitro-aerial spirits brought by the 

 nerves, an aerial ferment may not in addition come 

 into the stomach directly from the mass of the 

 blood. 



I conclude that the digestive liquid of the stomach 

 is not very different in kind from saliva ; for saliva 

 seems to consist of nitro-aerial particles deposited in 

 the maxillary glands by the nerves and there mixed 

 with a serous juice derived from the blood : and that 

 it is to be believed that the saliva mixed in mastica- 

 tion with the food conduces not only to its deglutition 

 but also in no small degree to its digestion. 



If the stomach be quite empty of food, its internal 

 membranes are, as is probable, pinched by the 

 nitro-aerial particles, and hunger seems to arise from 

 this. 



The food is concocted by the ferment of the 

 stomach into chyme, which, when it has passed into 

 the duodenum immediately meets the bile, by which, 

 as by a new ferment mixed with it, it is further 

 fermented and concocted. For as the bile is com- 

 posed of saline-sulphureous particles, it necessarily 

 effervesces in a high degree with the chyme, which 

 is full of nitro-aerial particles ; but to what ex- 

 tent bile partakes of a fermentative nature may 

 be gathered from this, that if it is mixed with a 

 farinaceous mass it raises it and ferments it, as has 

 been elsewhere stated. 



OF THE FERMENT OF THE PANCREAS 



I think that the pancreas must also be counted 

 among the viscera serving for digestion, inasmuch 



