22 



EXERCISE y 



GRAPHIC OF ARTERIAL PRESSURE, INFLUENCE OF VAGUS, OF ATROPINE, 

 AND OF FARADIZATION OF THE SPINAL CORD. ANTIDROME CON- 

 DUCTION IN DORSAL COLUMNS OF SPINAL CORD 



I. A decapitated carcase supplied with pulmonary ventilation is pro- 

 vided as for exerc. IV. See, as for exerc. IV, that it is in good order. Set 

 the Einger-Locke warming and get ready the instruments and apparatus. 

 For the present exercise these are : 



(1) A straight glass cannula about 4 mm. external diameter, with neck 

 and oblique-mouthed smooth-lipped opening at the nozzle end, for insertion 

 into artery ; this end is of about 2 mm. diameter, distal to neck. The cannula 

 about 3 cm. long. The cannula should have been previously cleaned and 

 boiled in water. It should now lie ready for use in a small vessel of Ringer- 

 Locke fluid, which need not be warm. It is useful to have two such 

 cannulae ready, one having a finer nozzle than the other. It is well to use a 

 cannula with as free a bore at its arterial end as the artery will take. 



(2) A glass filler-up, i. e. a piece of straight glass tube about 8-9 mm. 

 wide for 10 cm. of its length and beyond that at one end drawn out into 

 a coarse capillary of about 2 mm. external diameter and at least 6 cm. long. 

 Its other end is armed with 20 cm. of rubber tubing. It should lie ready 

 filled with Ringer-Locke fluid in the vessel with the cannula. 



(3) The mercurial manometer (p, fig. 5, PI. II) attached to the kymo- 

 graph, with clean mercury enough to give a column of 12 cm. height in each 

 limb of the manometer. The upper end of the proximal limb of the manometer 

 is armed with about 4 cm. of strong rubber tubing with a clamp (a) on it. 

 If the mercury column is in order, close this clamp. The side-branch of the 

 proximal limb of the manometer is connected by thick rubber tubing 

 (pressure-tubing) (b) with a glass T-piece. One branch of this latter has 

 attached to it a rubber tube about 1-5 m. long, leading to a pressure-bottle 

 (d) of 2-litre capacity, placed in a wooden lidless box, this latter suspended 

 by a strong cord passing over a pulley attached to the ceiling, the cord 

 descending again to a cleat on the kymograph or animal table. The pressure-' 

 bottle contains a litre of either aqueous half-saturated MgSO or NagSo^ 

 solution, or of lj)er cent. sod. citrate solution. Astrong screw-clamp (e) opening 

 by hinge, and therefore allowing the clamp to be applied without undoing the 

 tube, is placed on the tube from pressure-bottle to manometer, as close as 

 practicable to the latter. 



