ADVANCED EXPERIMENTAL PHYSIOLOGY 149 



CHAPTER XXXV. (Advanced}. 

 THE HEART. 



The Contraction Curve and 

 Latent Time of the Stanniused 

 Heart. Expose the heart of a 

 pithed frog. Pass a ligature 



under the two aortae, and draw ISBBBSSil^^^BRi H * 

 the ends exactly round the white ' 



T^SfPr^SBBiSi^BP J 

 sino-auricular junction. Tie the 



ligature. The sinus continues to ^^K^S^^BS^^BII -= J 

 beat, while the auricles and ven- ^MJ|^^^^|9|jpBlifcj| 

 tricles stand still. Record the ^^^^^_^^^^^^^_ 

 heart by the suspension method. B^fl BU 15 



Two needle electrodes passed 

 through a piece of cork are pinned 

 in such a position that one touches 

 either side of the heart. The 

 drum is set at a moderately fast 

 rate, and the trigger key is placed 



in the primary circuit. A short BSBI Efl 



circuiting key is placed in the 

 secondary circuit, and the coil is 



arranged to give a break shock sgiMHHMH^MMWWKBW #A * 

 just perceptible to the tongue. ^SSB&SBRSSSSSlii ^" 



HH^VraHBi& * 



and set the drum so that the 



striker is just beyond the trigger 



key. Then close the latter. Place SJBPSBHBB^BI^BB ^M 



the lever at a tangent to the 



drum, and bring the writing 



point lightly in contact. Then .... .^ 



open the short circuiting key HBJtHBlBB^^BlLBI "2-5J 



and start the drum. Stop the HBgH^^BH^^Bfll Jl-s 



drum immediately after record- BRBBBSl^^Efli l'l> 



il " iia 1^| 



-.fS 



short circuiting key, then close ^^^^^^^^^^^s^ 



the trigger key; lastly open the flB^^^^BI^^^BlB *" 



short circuiting key. Bring the 



