CHAPTER I 

 HISTORICAL INTRODUCTION 



Understanding of the function of the salivary glands has come 

 about slowly. Of course the lubricating and cleansing actions of 

 saliva were known since earliest times, and some details of the 

 anatomy of the glands were known. For instance, Galen in De usu 

 partium had indicated the positions of the major salivary glands 

 and had even described the opening of the submaxillary duct in the 

 mouth. With the revival of learning detailed anatomical descrip- 

 tions of the glands appeared, beginning with the publication of 

 Vesalius' de Humani corporis fabrica in 1543 ; other anatomists (e.g. 

 Steno, Wharton, Rivinus, Nuck) expanded these observations, and 

 established the existence of ducts conveying a secretion to the 

 mouth. These anatomists were passionate disputants, greatly con- 

 cerned about priority of discovery; to them the function of the 

 structures they discovered was a subject for speculation, but not 

 for experiment. The exception was Regner de Graaf, who pub- 

 lished in 1677 his brilliant study of the pancreatic secretion, de 

 Graaf prepared dogs with chronic fistulae of both the pancreatic 

 and submaxillary ducts (Fig. 1.1). In addition to observations on 

 pancreatic juice, he must have made many on submaxillary secre- 

 tion, but unfortunately these were never published and we have to 

 be content with less than a page in which he records that salivary 

 flow increased during mastication and swallowing as well as in 

 response to the smell and taste of food. He emphasized the role of 

 saliva in facilitating the swallowing of food. It is curious that such 

 a valuable experimental method as the production of fistulae 

 should have fallen into oblivion and not have been used again until 

 it was revived by Bernard (1856) and Heidenhain (1868) and later 

 developed extensively by Pavlov (1897). 



During the eighteenth century considerable progress was made 

 in the study of gastric digestion, notably by Spallanzani (1784), 

 who made ingenious experiments on intragastric digestion in many 

 species. He apparently did not consider saliva as contributing to 

 digestion. Bordeu (1 751) in a speculative account of the physiology 

 of the glands, recognized the main circumstances under which 



P.S.G. — B I 



