78 



EXEECISE Xll 



saliva is seen to ooze from the cut in the duct and shows better the lumen of 

 the duct. Taking the tied ligature with the left hand, insert with the other 

 the cannula into the duct in the direction towards the gland. The cannula, if 

 passed for 10 mm. or so into the duct, is gripped by it and requires no 

 ligation to hold it there. When the cannula is in, release the ligature, and 

 let the cannula lie, supported on the tissues. Faradize again for 5" ; saliva 

 flows into the cannula. 



Bring the barometer-tube to the table into a convenient position and con- 

 nect it with the duct of the rubber tubing. Faradize for 15". Saliva enters the 

 barometer-tube and flows along it during the stimulation at the rate of about 

 5 cm. per 10". As the stump of lingualis for stimulation is very short, it may 

 be better, for avoiding escape of current, to stimulate it by the unipolar faradiza- 

 tion method. The stigmatic electrode for that purpose is figured (PI. VI, fig. 4). 

 Note that no swallowing ensues on the stimulations. Set the barometer-tube 

 vertical and faradize again. Note pressure. Collect some saliva for chemical 

 examination. Faradize and observe the colour of the tongue on its right side. 



Obs. 56. QVI. Fill the needle-syringe with pilocarpine nitrate, -2 per cent, solution. 



Pilocarpine and Inject -5 c.c. into a saphena vein (see exerc. V). Observe the effect upon the 

 salivary .. _ 



salivary flow.J 



secretion. 



Obs. 57. 

 Atropine and 

 salivary 

 secretion. 



Obs. 58. 

 Air-embolism. 



VII. Fill the needle-syringe with 1 per cent, atropine sulphate solution. 

 Prepare the saphenous vein at the ankle (cf. exerc. V). Inject half the 

 syringeful into the vein. Faradize the corda tympani again ; note the result. 



VIII. Expose a jugular vein low down in the neck. Insert and ligate into 

 it a glass cannula directed towards the heart. Attach a short piece of rubber 

 tubing to the cannula. Inject with a syringe some air into the vein ; note the 

 effect of the air-embolism. 



Obs. 59. 

 Expansion of 

 the lungs by 

 aspiration : 

 pneumothorax. 



IX. Two pressure-bottles of about 2 litres capacity each, and with their 

 lower tubulures connected by a rubber tube about -75 metre long, are provided. 

 Each bottle is about one-third filled with water. One of the bottles (a) has in 

 its upper tubulure a stopper (cork or rubber) through which pass two glass 

 tubes. One of these, of about 6 mm. outer diameter, is narrowed, giving a 

 constriction about 1 cm. above its lower end, so that the trachea can be secured 

 to it by a ligature and will not slip off it. The upper end of the other 

 glass tube has a short piece, e.g. 3 cm., of rubber tube attached that can be 

 closed by a spring clip. The two bottles are placed side by side on the table. 

 The upper tubulure of a should have an internal diameter of at least 3 cm. 



Dissection. The carcase, detached from the ventilation-pump, is placed 



