154 



PRACTICAL PHYSIOLOGY 



CHAPTER XXXVII. (Advanced). 



GASKELL'S CLAMP AND THE EFFECT OF LOCAL WARMTH ON 



THE HEART. 



Gaskell's Clamp and the Effect of Heat on Sinus and Ventricle. 

 The heart of a large frog or toad is required. The contraction of the 

 auricle and ventricle are registered by means of two levers which are 



FiG. 154. Gaskell's heart clamp and levers for recording the contraction of 

 auricle and ventricle. 



attached by means of threads to the apex of the ventricle and auricle 

 respectively ; the one lever is pulled downwards against an elastic 

 spring arid the other upwards. The heart is held fast by means of a 

 screw clamp in the auriculo-ventricular groove. 1 The clamp is provided 

 with a fine screw, which can easily be adjusted so as to hold the 

 heart firmly without injuring the tissue (Gaskell). In this way the 

 contractions of auricle and ventricle are registered separately. Take a 

 thick copper wire, bent into a hook at one end, and place the hook 

 round the sinus. Warm the other end of the wire in a flame. 



1 A screw clip, to the bars of which cork wedges are fastened, will do for the 

 clump. 



