4o6 THE POPULAR SCIENCE MONTHLY. 



to resist flexion of the joints, the muscles of the lower jaw and neck 

 being generally first involved, those of the lower extremity last. It 

 might possibly be confounded with stiffening from extreme cold or 

 spasms; but frozen limbs yield a creaking noise when forcibly flexed, 

 from breakage of the congealed moisture, and spasmodic contraction 

 resumes its morbid position on removal of the correcting force. Not 

 so post-mortem rigidity. 



Putrefaction succeeds rigidity as a bluish-green tint of skin, com- 

 mencing usually on the lower part of the abdomen and spreading over 

 the body. Similar gangrenous appearances may occur during life, but, 

 besides their more circumscribed extent, the invariable presence of a 

 line of displaceable redness at the confines of the living tissues is a con- 

 stant and characteristic distinction. 



The desideratum, however, is some infallible proof of death whereby 

 this state can at once be decided without waiting for the more tardy 

 supervention of these -^ositix q\j post-mortem phenomena. 



Neither the cadaveric aspect nor coldness and lividity of surface 

 are constant or unequivocal signs. The cessation of the heart's action 

 beyond five minutes is undoubted evidence, but it is impossible to 

 acoustically determine this with absolute certainty, even when aided 

 by the stethoscope, as the sense of hearing may be fallacious in deli- 

 cate cases. Neither is the impei'ceptibility of the respiratory move- 

 ments of the chest perfectly decisive. Conclusions from experiments 

 on the eyes, by trying to excite the pupillary muscles by physiological 

 agents, or by examining the fundus with the ophthalmoscope so as 

 to observe certain changes supposed to be essentially post-mortem, are 

 invalidated by the comparative unimportance of these organs to gen- 

 eral vitality. The same uncertainty holds as to the effects produced by 

 tightly ligaturing a limb, as there might be complete occlusion of its 

 vessels and consequent arrest of its circulation without necessarily 

 fatal results. The changes induced in a polished needle inserted deeply 

 into the living tissues may be closely simulated by non-vital causes. 

 Circumstances might also obscure the difference between the contents 

 of vital 2lvA post-mortem vesication. 



The possibility of absolutely deciding, in doubtful cases, as to the 

 presence or absence of vitality depends on the possession of artificial 

 means wherewith to sensibly demonstrate the minimum activity of each 

 of the essentially vital processes, the utter negation of the various spe- 

 cific reactions under their appropriate tests being infallible evidence of 

 death. The different available measures vary in their degree of simplic- 

 ity and facility of application, but the results are all equally conclusive. 



The validity of the respiratory test results from the fact that even 

 during the most reduced state of vitality carbonic acid is perpetually 

 generated in the system, and extricated therefrom through specially 

 adapted air-passages, where its escape can invariably be detected by 

 proper appliances. 



