HYDE: EXPERIMENTS ON THE SKATE. 



45 



Hiirthle cardiac records above, gill-arch lever records below. Time, 

 five seconds. Cardiac and respiratory rate decreased, force and blood 

 pressure increased for about three minutes, then quite normal for about 

 thirty minutes. First effect often irregular and spasmodic, especially for 

 cardiac rhythm. 



Curve 20. Effect of m% CaCla. 



Curve 20. 



Upper curve respiratory, lower cardiac. Levers directly attached to 

 heart and gill arch. Cardiac and respiratory rates first decreased, force 

 increased; irregular prolonged diastole and inspiratory phases. 



The results following injections of MgS04 solutions are 

 summarized in table IV, and illustrated in the curves. It was 

 observed that an m/64 or m/8 MgS04 had a more depressing 

 influence on respiration than on cardiac activity. The rate was 

 either unchanged or less, but force and blood pressure usually 

 sHghtly greater for cardiac, while rate and force of respiratory 

 activity were generally decreased. 



An m% or m/1 solution produces for about two minutes an 

 increase in blood pressure followed by a decrease. Respiratory 

 and cardiac rate and force both decrease, but occasionally the 

 force of the heart's activity is first increased. Sensory re- 

 flexes are all reduced. With every strength of the solution the 

 force and rate of the respiratory rhythm and the cardiac rate 

 were decreased, but blood pressure and cardiac force were in- 

 creased or decreased after a previous increase. With strong 

 solutions, e. g., m/1, diastole and expiratory phases predomi- 

 nated and the activities may become irregular, but an m/8 

 CaCl2 overcomes the toxic effect and increases the force of the 

 respiratory phase and blood pressure. 



