108 



EXERCISE XVII 



vol. 1, p. 157) of the blood-plasma ; neither 

 does it maintain the due viscosity of the 

 blood, on which the normal arterial pressure- 

 head so largely depends. 



To remedy these defects a very effective 

 saline fluid has recently been devised by 

 Bayliss (1916, Proc. Boy. Soc. B. vol. Ixxxix, 

 p. 380 ; Med. Besearch Comm. : Beport of 

 Surgical Shock Comm. No. 1, 1917). Bayliss's 

 fluid is gum (arabic) 6 parts. Sod. Chi. O. 9, 

 water 100. It possesses approximately the 

 same viscosity coefficient as the whole blood 

 and the same osmotic tension as the plasma. 

 The gum contains requisite amoimts of Ca 

 and K, so that addition of these is un- 

 necessary. It restores the art. pressure to 

 its original height when injected in volume 

 equal to that of the blood removed, and the 

 A. P. retains 88 per cent, of its height even 

 at the end of three hours or more. The 

 colloidal gum solution is made with 9 per 

 cent. NaCl instead of pure water, because 

 that strength of saline, being isotonic with 

 the blood, prevents the laking of the red 



blood corpuscles which would ensue with 

 the gum-suspension alone. Bayliss's fluid 

 restores the A. P. after haemorrhage much 

 more fully and durably than any 'normal' 

 saline ; it has been found of great use in the 

 treatment of haemorrhage (Bayliss, Intra- 

 venous Iff jection in Wound ShocJCjIjond. 1918). 



§ VIII. It might seem more convenient 

 to use a carotid for the haemorrhage ; but 

 if this be done the manipulations are liable 

 to irritate the vagus nerve lying alongside 

 the artery ; such irritation tends to make 

 the arterial pressure irregular and to disturb 

 the observation of the pressure. 



Ohs. 81. The hindering of clotting of 

 drawn blood by addition of pot. oxalate 

 (' decalcification ') was discovered by Arthus 

 and Pages, 1890 {Archives de physiologie 

 normale etpathologique, p. 739). Freecalcium 

 ions are essential for thrombin formation. 



Ohs. 82. Hammarsten's method ; and cf. 

 Practical Physiol Beddard, Edkins, Hill, 

 Macleod, and Pembrey. 



EXERCISE XYIIl 



SPINAL KEFLEX ACTION IN A FLEXOK MUSCLE (TIBIALIS ANTICUS). 

 PKOPRIOCEPTIVE REFLEX. COMPARISON BETWEEN REFLEX AND 

 PERIPHERAL CONTRACTION 



[Square brackets indicate those parts of the exercise which can be omitted at its 



first performance.] 



I. See that the decapitate preparation is properly ventilated and in good 

 condition. Set the Einger-Locke fluid warming in readiness for operation. 



II. Get ready the recording myograph and stimulating apparatus (text- 

 fig. 37) on the experiment table, to which the operation table can be brought 

 close. The vertical spindle carrying the myograph recording-drum has 

 clamped to it below the drum a horizontal rod which revolves with the drum. 

 A vertical standard which can be placed within reach of the horizontal rod 

 carries a key for the primary circuit of the inductorium ; a lever in this key 

 projects so that when it is' at an appropriate height the horizontal rod in its 



