irtgn.i proceedtnGs of uKiTed states national museum. 2'25 



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ToB. VlflI,i^o. 15. Washington, ]l. €. July 





THE INFLUENCE OF VARIATIONS OF TEMPERATURE UPON THI] 

 RATE AND THE WORK OF THE HEART OF THE SLIDER TERRA 

 PIN. (PSEUDEMYS RUGOSA.) 



Br Dr. H. Q. BX: VER, U. S. IV., 



Curator, section of Materia Medica, U. S. National Museum. 



In the studies from the Biological Laboratory of the Johns Hopkins 

 University, vol. iii, No. 2, I briefly described the results of some experi- 

 ments made on the heart of the frog and terrapin with regard to the 

 influence upon them of oxygenated and non-oxygenated blood, and of 

 blood in various degrees of dilution. These results showed very clearly 

 that the influeuce of oxygenated blood upon the heart with regard to 

 both its rate and work done in a unit of time was a most decided one. 

 The manner in which oxygenated and non-oxygenated blood was pre- 

 pared was as follows : A quantity of defibrinated calf's blood was pre- 

 viously mixed with an equal volume of Einger's saline, divided into two 

 portions and each portion i)ut into a bottle ; one was allowed to stand 

 quiet for a while, the other was shaken up for a few seconds every now 

 and then until a perceptible diflerence in color was noticed. This was 

 brought about in from five to ten minutes. Then the contents of these 

 two bottles were turned into separate Mariotte's flasks, which were con- 

 nected with inflow cannulas inserted into the great veins leading directly 

 into the sinus, and when the time came for an observation the blood was 

 allowed to run through the heart and its effect noted. It was noticed 

 that the rate and the amount of work were always increased on supply- 

 ing the heart with oxygenated blood; the former was increased from one 

 to five beats per minute, the latter all the way from 30 to 175 per cent. 

 A very slight agitation of the blood before returning it into the flask 

 would increase the work done, even when the diflerence in color was 

 not perceptible to the eye, a point of great importance in connection 

 with experiments with drugs on the heart. 



The results of the second group of experiments were, that the max- 

 imum amount of work was not done b^^ the heart when supplied with 

 simple undiluted defibrinated calf s blood. As a diluent the often- 

 quoted Einger's saline was used, the composition of which is as follows : 



CO. 



Normal salt solution (0.75 per cent.) 100 



Calcium clilor. sol. (1.390) 5 



Sod. bicarb, sol. (0.50 per cent.) 2.5 



Sol. pot. chloride (1.0 per cent.) 0.75 



Proc. Nat. Mus. 85 15 



