BY DR. LAUDER BRUNTON. 465 



submaxfllary duct, the student must now place himself before a 

 mirror, with a bright light directed into the mouth. Fill the 

 mouth with vapor of ether, or chew a piece of pyrethrum. Turn 

 the end of the tongue back against the palate. At the root of 

 t\\efrsenum linguae a papilla with a little black dot is seen at 

 each side of the middle line. From these two dots, which mark 

 the orifices of Wharton's ducts, the saliva will be seen to issue. 

 Insert the end of the canula into one of them, and hold it 

 steadily in its place. The entrance of the canula is attended 

 with an unpleasant sensation, not amounting to pain. At first 

 the canula fills pretty rapidly, but as the effect of the ether 

 passes off, the flow soon diminishes. If it is desired to collect 

 the secretion, a piece of India-rubber tubing must be attack \ 

 to the wider end of the canula before inserting it. 



Insertion of a Canula into the Parotid Duct. As it is 

 hardly possible to insert a canula into one's own parotid duct, 

 a second person must be emplo3*ed, who should sit opposite a 

 good light and chew pyrethrum root as before. The method 

 is as follows: Draw one angle of the mouth outwards and 

 forwards so as to stretch the cheek. Opposite the second 

 molar tooth of the upper jaw the small papilla is seen which 

 marks the orifice of Stenson's duct. Insert the canula and 

 hold it steadily but carefully in its place, then a third person 

 may blow into the mouth some vapor of ether, or introduce a 

 little diluted tincture of pyrethrum. 



By these methods a sufficient quantity of secretion can be 

 collected for the investigation of the leading properties of the 

 two secretions. Both possess the property of determining the 

 transformation of starch and sugar. 



87. Study of the Secretions of the Salivary Glands 

 in Rabbits. The ducts of the salivary glands in rabbits 

 are too small to allow of the easy introduction of a canula, 

 but the secretion may be readily studied by cutting the duct 

 across. The saliva escapes from the cut end and collects in 

 drops. When the secretion is slight, it may be rendered readily 

 visible by putting over the end of the duct a piece of bibulous 

 paper reddened with litmus. The saliva is absorbed by the 

 paper, and produces a blue spot, which increases in size, more 

 or less rapidly, according to the rate of secretion. 



* Parotid Gland The duct runs from behind forwards 



across the masseter muscle about its middle, covered by fascia. 

 It has branches of the facial nerve on each side of it, and is 

 parallel with the transverse facial artery. At the anterior 

 edge of the masseter it takes a direction towards the middle 

 line, in order to enter the mouth. 



If a vertical incision is made in a line with the cornea 

 through the skin and fascia of the cheek down to the masseter, 

 30 



