HYDE: EXPERIMENTS ON THE SKATE. 



49 



Curve 28. Effect of Na2HP04 m/8. 



Curra 28. 



Upper, cardiac and blood-pressure Hiirthle manometer curves. Rate 

 little less, force slight increase. Lower, respiratory record; shows rate 

 unchanged, force decreased, pressure decreased. 



Curve 29. Na2HP04 m/4. 



Cnrre 29. 



Upper, cardiac and blood-pressure Hiirthle curves; show fall in blood 

 pressure and for three minutes almost cessation of cardiac action. Lower, 

 respiratory, force much decreased. 



Curve 296. 

 tions. 



Effect of gradually increasing strength of Na2HP04 solu- 



^AMAAAA 



Upper, respiratory gill-arch lever curves show that with increasing 

 strengths from m/64, m/32, m/8, m/4, solutions that the rate increased 

 and force decreased from the normal and that this solution is more favor- 

 able to respiration as stimulating rate. Lower, cardiac apex lever curve 

 shows that the rate remained practically unchanged except in m/4, when 

 it became rapid and force decreased gradually from the normal. 



The influence of NaOH solutions is briefly tabulated in 

 table VII. It is demonstrated that it acts, augmenting in all 

 concentrations, on the force of the heart-beat and has not the 

 same but rather a depressing effect on the respiratory center. 

 The OH ions here, as in the Na2C03, are the stimulating fac- 

 tors, but act more powerf ally than in Na^COa solutions. The 



