92 ELECTRO-PHYSIOLOGY CHAP. 



tardation of death by previous protracted cooling (artificial cold- 

 bloodedness), which can be produced either by dividing the spinal 

 column high up (Bernard), or by irrigating the skin of the belly 

 with cold salt solution. In rabbits cooled in this way to 20 C. 

 in 610 hours, the direct muscular excitability persists for 68 

 hours after death (Israel, 49). 



There can be no doubt that the immediate cause of death in 

 excised muscle is the interruption of the nutritive stream, and of 

 the circulating blood in particular. Even in the living animal, 

 interruption of circulation in a muscle, or group of muscles, 

 produces paralysis in a short time, and eventually rigor. This 

 experiment is only partially successful in cold-blooded animals, 

 because their muscles, e.g. in Amphibia, though also dependent on 

 the circulation, exhibit the effects of ansemia at a relatively 

 much later period (Ktihne, 50). The muscles of frogs are 

 known to remain excitable for days, when all the blood has been 

 driven out by injecting the vessels with 0'6 / salt solution 

 (salt frogs). On the other hand, the striated muscles of warm- 

 blooded animals, especially of birds, are correspondingly more 

 sensitive, losing their excitability after a comparatively short 

 time, and finally becoming rigid (Schiffer, 51) when the circula- 

 tion is completely interrupted. It is, however, possible to 

 restore or preserve excitability, when reduced or abolished by 

 anaemia, by artificial transfusion of arterial blood. The time up 

 to which this will succeed after loss of excitability is longer in 

 proportion to its normal persistence (Brown-Sequard, 46). The 

 excitability of smooth muscles in warm-blooded animals is much 

 less dependent upon the circulation, and they are in this respect 

 more like the striated muscles of cold-blooded animals. 



Many unjustifiable assertions have been made with regard 

 to the rapidity of death in smooth warm-blooded muscles, and 

 their sensibility to alterations of metabolism, because the spon- 

 taneous movements of certain smooth muscular organs (e.g. 

 intestine) cease very soon after death, and along with them 

 excitability to artificial stimuli. But it may easily be shown 

 that this seemingly permanent loss of excitability is really 

 only produced by cooling, and that the sensibility to stimula- 

 tion makes its appearance again when the temperature is raised 

 artificially (Biedermann, 52). The muscular wall of the excised 

 intestine of mammals retains its vitality in a most surprising 



