204 The Physiology of Digestion [lect. 



stomach as out of all proportion to the movements or sensations 

 of that organ, believed that a nervous fluid having some share 

 in the digestion of food was poured into the cavity of the 

 stomach from the endings of the nerves. 



This solution by means of juices was, however, in Boerhaave's 

 opinion only a part of the digestive process. He joined with 

 the mechanical school in believing that the more fluid and 

 nutritious parts of various articles of food were expressed from 

 them by trituration in the stomach. He expressly taught that 

 the more solid and resisting framework of both animal and 

 vegetable food was not digested at all ; that digestion to a large 

 extent consisted in this, that by the solvent action of the juices 

 or by mechanical pressure the softer or more fluid material held 

 by the framework was either dissolved or pressed out of it. 

 In particular he 'thought that bones were not digested, only 

 crushed, and pointed to the white excrement, the album graecum, 

 of dogs fed on bone, as a proof of this. 



Boerhaave's positive mode of thinking put him more or less 

 in antagonism to the doctrines of fermentation, to which, as we 

 have seen, the chemical school were so attached. He seems, 

 moreover, to have distinguished between the chemical effer- 

 vescence of Sylvius and true fermentation, such as that of wine. 

 He regarded the action of the juices as a mere solution, not as 

 a proper fermentation. Nevertheless he held that solution and 

 trituration are, in digestion, aided by something else. He 

 thought that in the stomach, which is a closed chamber, but 

 with air present in it, the contents, exposed as they are to a 

 considerable heat, do undergo "an incipient fermentation, by 

 " means of which the chyle is impressed with the primary 

 '• principle of vitality." 



Such were the doctrines taught by Boerhaave in the early 

 years of the eighteenth century. They were very largely 

 accepted, and indeed became the dominant views. We find 

 almost the same teaching nearly fifty years afterwards when we 

 come to Haller, of whom we must now speak. 



The year 1757 may be regarded in a certain s^se as a red 

 letter year in the history of physiology, as marking an epoch, as 

 indicating the dividing line between modern physiology and all 



