292 



PHYSIOLOGY 



CHAP. 



conditions, without special treatment, it speedily ceases to beat). By means 



of a cannula tied to 

 the aorta, in the direc- 

 tion of the heart, he 

 caused blood or other 

 nutrient solutions to 

 circulate at a tempera- 

 ture of 38 C. under a 

 pressure corresponding 

 to the normal pressure 

 of the aorta. The fluid 

 keeps the seniilunar 

 valves closed, circulat- 

 ing through the coron- 

 ary system of the heart, 

 and flowing out again 

 through the opening in 

 the right auricle. The 

 cardiac cavity remains 

 empty. A heart thus 

 artificially fed is cap- 

 able of continuing its 

 activity almost nor- 

 mally for many hours. 

 The graphic record of 

 its movements can be 

 taken by means of sus- 

 pension, or (after oc- 

 FIG. 126. Engelmann's myograph for recording beats of frog's eluding the veins of 

 heart in situ, when suspended from the apex by a thread the right auricle) bv a 

 connected with a highly sensitive lever. The apparatus is a V- i + 



two-armed lever, one arm of which -is attached to a fine silk manometer applied 

 thread, the other to a long straw or strip of aluminium, which the pulmonary artei'V 

 magnifies the movements of the writing point on a smoked /CSp-ii-Mrt lQfM\ 

 surface. At the end of the thread is a fine glass hook, with v 31 

 sharp point, which is inserted into the tip of the apex, after 



cutting the fraenum by which the two layers of the pericardium JT rrn _, f - j _i 



are united dorsally. U- 1 116 tact that 



it is possible to keep 



the isolated heart of different animals alive for a comparatively 

 long period has been used as the start- 

 ing-point for a series of researches on the 

 nutritive medium, or external chemical 

 conditions, necessary to its survival. 



This work has familiarised us with 

 the so-called physiological solutions, 

 which are artificial nutrient fluids, 

 capable (at least for a certain time) of 

 replacing the blood, since they contain 

 all the elements necessary for sustaining FIG. 127. cardiograms taken from 



,i -i-f. f ,-, -, fL-t frog by Engelmann's method. .. 



the lite Of the heart. The importance 



of this subject exceeds the limits of the 



present chapter, for it may logically fork which vibrates 10 times 



be concluded that artificial fluids which 



are capable of sustaining the vitality of the excised heart will 



also maintain the vitality of other organs or isolated tissues, or are, 



Commencement of ventricular 



