SALIVARY SECRETION 



76 



(2) A piece of barometer-tubing, about 2 mm. bore and about 50 cm, 

 long, armed at one end with 10 cm. of small rubber tubing, and fixed 

 horizontally in a clamp carried by a chemical standard. A good plan is to use 

 a tall standard on large base, the standard tall enough to reach at least 10 cm. 

 higher than the experimental table on which the preparation lies. 



(3) Needle-syringe (see that this is clean and in good working order) and 

 atropine sulphate, 1 per cent, sol., as in exerc. V. 



(4) Pilocarpine nitrate, 2 per cent. sol. 

 (6) A watch-glass. 



III. Operation (PI. VI, figs. 1, 2). Place preparation supine, with limbs 

 symmetrically post-tracted by clip-weights. The symphysis of the mandible 

 is secured between the blades of a small retort-clamp, the under blade lying 

 just posterior to the canines, the screw-tooth in the other blade lying close 



Text-fig. 29. Mandible-clamp for bulbo-spinal preparation, carried by short 

 standard on a leaden base. To the right, the way in which the clamp engages 

 the mandible, the small projecting screw catching behind the symphysis as the 

 clamp-screw is turned. 



behind the symphysis of the jaw (text-fig. 29). This clamp is best fixed to the 

 stable standard by an obliquely adjustible screw-clamp, allowing the mandible 

 to be fixed in its natural position sloping upward and forward, the prepara- 

 tion being supine. 



Skin incision : along mid-ventral line from 1 cm. behind symphysis of jaw 

 in front to hyoid bone behind ; the hyoid can be felt through the skin in the 

 mid-line about 1 cm. in front of top of thyroid cartilage. From ant. end of 

 this incision a lateral one at right angles to it to the preparation's right side 

 as far as the ramus of the jaw ; from post, end of median incision a lateral one 

 at right angles to it and extending 3-4 cm. to the right. Reflect the skin 

 laterally as far as the outer border of the lower jaw (PL VI, fig. 1). Note the 



L 2 



