226 PROCEEDINGS OF UNITEI» STATES NATIONAL MUSEUM. [1885. 



With tbis saline mixture, the (liffeierit iintrieut liquids used in the 

 experiments were prepared ; the proportions \:irie(l all the way from 

 one of blood to one of the saline, to one of blood and twenty of the 

 saline. Most any of these solntious supplied to the heart in the usnal 

 manner from Mariotte's flasks caused th(^ heart to yield more work than 

 the simple delibrinated mammalian blood, but the mixture which proved 

 the most favorable to the performance by the heart of normal and uni- 

 form work for any length of time was found to be the one in which 

 equal volumes of l)lo(id and dinger's saline had been used. Hence this 

 l)roportion was used as a normal nutrient in all the subsequent experi- 

 ments of this nature. 



I propose here to supplemcTit the above results by some recent exjie- 

 riments made with a view of ascertaining the influence of blood of 

 different temperatures on the rate and work of the heart of the slider 

 terrapin. 



From the time when Calliburces (Claude Bernard, Systeme Nerveux, 

 392) first studied the influence of variations of temperatures on the frog's 

 heart, we know that the rate increased in direct proportions to the 

 temperature of the heart, whether the latter is isolated from the body 

 of the 'animal or left in situ. Shelsky, extending- these researches ( Ueber 

 die Veranderungen d.Erregbarkeit durch die Warme, Heidelberg, 1860), 

 working also with the frog's heart, ascertained that the automatic move- 

 ments of the heart might be kept up within temperatures ranging all 

 the way from 0° to 40° 0., but that beyond these limits they were 

 arrested, a recurrence of beats, however, taking place upon a return 

 of the temperature to within this physiological limit. 



Cyon (Ludwig's .Arbeiten, 180G, p. 43), in a most carefully con- 

 ducted series of experiments on the frog's heart, found that these limits 

 were somewhat variable ; that is to say, while some hearts stop beat- 

 ing at temperatures varying between 30° and 40° C, others continued 

 to beat when cooled down to —4° 0. From the more recent experiments 

 on the isolated dog's heart by Prof. H. Newell Martin (Philosophical 

 Transactions of the Royal Society, Part ii, 1883), we have furthermore 

 positive proof of the fact that the rate of beat of the mammalian heart 

 is directly dependent on the temperature of the fluid circulating through 

 that organ, and that the increased pulse-rate in the condition known as 

 fever can be sufficiently accounted for by the increased temperature 

 which the blood assumes during its course through the inflamed organs. 



While, then, the relation of the rate of beat of the heart of both warm 

 and cold blooded animals to variations of temperature is i)retty well 

 understood and established, the same can hardly be said as being 

 equally true with regard to the woric done. In those pharmacological 

 experiments on the hearts of cold-blooded animals, according to the 

 method which will be found described in the July number of the Amer- 

 ican Journal of the Medical Sciences for 1885, the amount of work done 

 by the heart forms one of the most important factors in the conclusions 



