272 THE ACTION OF THE LIVING CELL 



animals was indicated by the drop in surface tempera- 

 ture and blood pressure. Such reactions as these, 

 which always accompany shock, were never found to 

 follow immediately after the infliction of an injury, as 

 would be expected if the shock were due to a nervous 

 mechanism of any sort. In general, regardless of the 

 nature and magnitude of the inflicted injury, shock 

 does not supervene until approximately two hours fol- 

 lowing the injury. This fact of course suggested the 

 intervention of some relatively slow chemical process, 

 rather than a nervous one, and since the onset of shock 

 is the direct outcome of the injury, such a chemical 

 process must take place in the injured tissues. 



This conclusion was substantiated by three lines of 

 experimental evidence which have been discussed in 

 detail in the early chapters of this monograph. First, 

 ligation of an injured limb above the site of an injury 

 was found to prevent the onset of shock because it 

 prevented the absorption of materials from the wound. 

 If after several hours the ligature was loosened, then 

 the various symptoms of shock rapidly appeared, thus 

 indicating that the shock was due to the passage of 

 substances from the site of injury to the splanchnic 

 area. Secondly, histological examination of the in- 

 jured tissues disclosed the fact that, following injury 

 of any sort, the affected tissue cells undergo autolysis. 

 Such a process requires a definite time, and it is this 

 interval which must elapse between the infliction of 

 the injury and the onset of shock. From this observa- 

 tion, it was deduced that the primary cause of shock 

 was an endocellular toxin liberated by the tissues 

 incident to their autolysis. 



The validity of this conclusion was subsequently 



