80 



THYSIOLOGY AND TOXICOLOGY 



color and somewhat jelly-like appearance. The structure remained entire until it 

 was pressed upon or stretched, when it lost all regularity, and offered the appear- 

 ance under the microscope of a minutely granular mass, dotted with larger gra- 

 nules. The altered character of the muscle is illustrated in Fig. 12. 



Tis. 12. 



Appearance of muscailar fibre when mechanically disturbed after contact with venom. 



Efect on tlie IZeor<.— Continuing the study of the action of the venom on muscu- 

 lar parts, it remains to examine the extent to which the heart is influenced. 



This question is one of extreme interest, and of no less difficulty. It is so 

 important, however, in its bearings upon the causation of death in acute poisoning, 

 that I have spared no pains to investigate it by every means in my power. 



My first observations were made by exposing the heart of the frog, and observing 

 it before and after the animal was bitten. Many of these observations failed par- 

 tially, or entirely, owing to the frogs having survived long enough to pass into the 

 stage of secondary poisoning. 



In most of the cases of acute poisoning the rhythm and force of the heart became 

 affected before the respiration was suspended, and the organ continued to pulsate 

 more or less perfectly for some time after all voluntary and reflex motion had 

 ceased. 



It is scarcely requisite to detail these observations more fully, since examples 

 may be found in the chapter which treats of the action of the venom on the 

 batrachia. I shall therefore limit myself to stating that, under the influence of 

 Crotalus venom the batrachian heart becomes enfeebled, and acts more slowly; 

 that it continues to act after the limbs have ceased to respond to stimulus by reflex 

 acts, and that it usually stops before the motor nerves lose their vitality. 



As the heart of the frog is remarkably independent of the respiratory and other 



