vi] Sylvius and his Pupils. 153 



entering upon that line of inquiry. To Sylvius at least is due 

 the credit of shewing that there was no such necessary con- 

 nection between chemistry and spiritualism ; that on the 

 contrary the newer chemistry in its attempts to solve vital 

 problems trod the path of the most naked materialism. It is 

 probably to his thus opening up a line of inquiry into chemical 

 physiology free from all taint of mysticism that the great 

 influence which as a teacher he undoubtedly exercised was 

 largely due. 



Sylvius had the advantage over van Helmont of the know- 

 ledge of three important discoveries which were not made until 

 after the latter's death. Van Helmont knew only of the gastric 

 juice, the acid ferment of the stomach, and of bile as digestive 

 juices ; for we may omit his stercoraceous ferment of the caecum. 

 Sylvius knew of others. We have already seen that in 1655 

 and 1661 Wharton and Stensen discovered the submaxillary 

 and parotid ducts. On the importance of these two discoveries 

 with reference to the physiology of secretion I have already 

 spoken ; they were still more important as regards digestion. 

 Stensen paid little attention, and Wharton hardly any at all 

 to the digestive uses of saliva; but S}dvius seized at once on 

 its importance, and as we shall see attributed to it very large 

 powers. 



He was also through the investigations of a pupil of 

 his led to recognize the possibly great uses of another digestive 

 juice. Wirsung had we have seen discovered in 1642 the 

 pancreatic duct, and appears to have observed the pancreatic 

 juice; but he did not pursue the subject, and indeed his 

 discovery remained barren until one of Sylvius' scholars took 

 the matter up. The work of the latter is so interesting an 

 example of the physiological experiments of the time that I 

 venture to speak of it in some detail. 



Regner de Graaf, born in 1641 at Schoonhaven in Holland, 

 of a good family, studied under Sylvius at Leyden, and after 

 graduating and travelling, practised for some years at Delft, 

 where he died in 1673 at the early age of 32, having in the 

 previous year refused to succeed to the chair at Leyden, just 

 vacant by the death of his late master Sylvius. While at Delft 





