HYDE: EXPERIMENTS ON THE SKATE. 

 Curve 33. Effect of m/4 NaOH solutions. 



51 



Upper curves, blood pressure and force of cardiac rhythm increased. 

 Lovi^er, respiratory activity decreased in force, rate increased. 



From the series of experiments with different concentra- 

 tions of urea solutions the conclusion is drawn that injection 

 of urea solutions of high concentrations, 2m to 4m, increases 

 force of respiratory and cardiac activity mainly. The rate is 

 practically unchanged, and weaker solutions are quite indiffer- 

 ent on blood pressure, cardiac and respiratory activity. It has 

 been found by Schroder*^^ that selachian's blood normally con- 

 tains 2.6 per cent of urea, and Baglioni" found that the selach- 

 ian's heart beats longer in urea than in NaCl. According to 

 Loeb it is due to the OH ions which are present when the dis- 

 sociation of the urea occurs. A weak solution of m/20 of 

 Na2C03, to which a 2m urea solution has been added, greatly 

 increased the force of cardiac action and blood pressure. 



Table VIII. Effect of urea solutions. 



Curve 34. Urea m/1. 



I u 



6. Schroder. V. z,eitschrift fiir Physiologische Chemie, XIV, S. 596. 



7. Baglioni. Zentralblatt fur Physiologie, 1905, XXX, No. 12. 



