144 APPENDIX 



Obs. 28, 29. These do not always, at least as a student's exercise, succeed in demonstrating 

 very convincingly the liberation of adrenalin on stimulation of n. splancJmicus. The failure 

 may be due to the amount liberated being sometimes very small owing to exhaustion of the 

 gland. A convincing demonstration of the splanchnicus as ' secretory' to the adrenal can be 

 shown, although in a manner scarcely open to performance by the student himself, by aseptic 

 ablation of superior cervical ganglion of sympathetic, and later, after the wound has healed, 

 faradization of distal splanchnicus. The denervated pupil dilates widely on faradization of 

 the nerve. The denervated pupil is an extraordinarily delicate reagent for adrenalin entering 

 the blood-stream. 



Obs. 32. Advantage is taken of the abdominal contents being exposed for the student to 

 see the mesenteric lymphatics as they appear when containing chyle ; students may mistake 

 them for nerves, which indeed to the naked eye they resemble To ensure chyle the animal 

 should have a meal of fat — more effectual than milk — 9-18 hrs. before the class-hour. 



The contingency that the lacteals when first seen may be taken for nerves is not fanciful 

 or unlikely. Aselli indeed, when he first noticed them, so mistook them. He says ' Eos primo 

 aspectu nervos esse ratus ', but adds ' non magnopere moratus sum ' ; and then he called his 

 friends Tadini and Septali to see the new sort of ' veins ' he had discovered, pricking these 

 vessels to show the milky fluid they held {De Lactibus sive lacteis Venis, p. 19 ; Milan, 1627). 



EXERCISE VIII 



Obs. 36. In the instructions is bracketed as optional ; the stenosis induced does not 

 very closely fulfil the conditions of aortic valve stenosis. The observation does not, however, 

 in the hands of a practised student, endanger the next and more important experiment, aortic 

 incompetence. 



Obs. 37. As stylets, hard drawn brass wire No. 9 S. W. G. (-144 inch diam.) or No. 10 

 S. W. G. (•128 inch diam.), or No. 11 is suitable. The stylet may be about 15-18 cm. long. 

 The end introduced into the artery should be oiled and smooth but flat across, not conical. 

 If not abruptly flat-ended it is liable to slip past the valve without engaging in a cusp. 

 The valve-lesion made consists almost invariably of detachment of a major part of the 

 middle of the attached border of a cusp. 



A suitable membrane-manometer readily made by a laboratory mechanician is the 

 following : Its dimensions are larger than those usually described and thus more easily 

 manipulated. It works quite satisfactorily for observations of the kind required by the 

 exercise. It consists (see text-fig. 25, p. 52) of a turned brass block bored horizontally with 

 a 3 mm. smooth boring right. through, and again at right angles vertically to meet that boring 

 but not to pass beyond it. The upper end of the vertical boring is enlarged into a shallow 

 circular cup 14 mm. in diameter and 2-5 mm. deep. A couple of brass tubes of the same 

 3 mm. internal diameter, and fitted each with a stop-cock, are screwed into the sides of the 

 brass block, their tubulures continuing the block's horizontal boring. Their free ends are 

 turned down in the lathe to allow rubber pressure-tubing of 2 mm. bore to be passed over 

 them without difiiculty though fitting tightly. A circular shelf is left round the small cup- 

 like excavation at top of the block. On this rests the rubber membrane. A brass ring 

 rests on the shelf above the membrane, and this and the membrane are clamped watertight 

 by a brass screw cap tapped with a thread for a male thread cut on the outer face of the 



