228 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. [1885. 



supplying liquids must be taken during the course of an experiment. 

 This becomes more especially necessary when working in a room which 

 is artificially heated and subject to sudden changes. A fact worth not- 

 ing in this connection is the peculiar systolic standstill which was pro- 

 duced by the sudden change of the supplying fluids from a lower to a 

 higher temijerature. During this systolic arrest the ventricle became 

 exceedingly small, looking pale and bloodless, while the auricles became 

 very mu(;h enlarged and overdistended with blood, which they were 

 unable to force into the contracted ventricle. This apparently shows 

 that warmth is a most decided cardiac stimulant, especially so far as the 

 ventricle is concerned. As, however, the temperature became equalized 

 the ventricle began to become gradually relaxed and admitted the blood 

 from the overdistended auricles, which, in spite of their having been 

 much overdistended for sometimes one-half minute, showed not the 

 slightest sign of weakening. 



Experiment IV. 



fFebruary 7, 1885. Terrapin, 680 grms. Biaiu and spinal coid destroyed. Heart exposed. Can- 

 ulas in left superior and inferior venae cavie and in Tiplit and left aortse. Pig's blood and Eingef's 

 saline u.sed as a nutrient in the proportion of 1: 1. Venous pres.sure, 3.5 c. m. Arterial pressure. 

 15 c. m.] 



* Terrapin in box. 



t Auricles contracting .sluggishly. 



I No auricular systole occurred. 



§ Five long tonic ventricular contractions to one imperfect and incomplete auricular. 



