336 



Dr. A. J. Wall. On the 



[June 16, 



coagulable purple blood-like fluid. In addition the whole of the neigh- 

 bouring vessels are intensely injected. This injection gradually 

 lessens as the site of the poisoned part is receded from, so that a 

 bright scarlet ring surrounds the purple area, and this, in its turn, 

 fades into the normal colour of the neighbouring tissue. At the 

 margin also the purple blood-like fluid is replaced by a pinkish serum, 

 which may often be traced up in the tissues surrounding the vessels 

 that convey the poison to the system. In one case in which the 

 victim was bitten on the hand, I traced this effusion around the veins 

 as high as the elbow. The local appearances differ considerably in 

 different cases, varying from those excessive ones just described to a 

 mere hyperemia. It has been asserted that these changes are merely 

 the result of haemorrhage from the divided vessels. But this will not 

 account for the pain or for the intense injection of the surrounding 

 parts, or for the fact that should the bite not prove fatal the site of it 

 nearly always suppurates. The real explanation is that cobra poison 

 is an intense irritant and produces acute inflammation. Thus, if a 

 small quantity be placed in the eye, the most severe inflammation of 

 the conjunctiva follows. The existence of this local inflammation is 

 of great value. It takes place with startling rapidity, one minute or 

 less producing marked hyperemia. This local hyperemia is, there- 

 fore, the first indication that we can obtain that snake poison has 

 really entered the system. As life itself depends upon the rapidity 

 with which snake poisoning can be recognised, it will be seen that this 

 is a matter of the greatest practical importance. 



An interval now occurs before any fresh symptom is noticed, but 

 the length of it varies greatly in different cases. In dogs bitten by 

 cobras the average of four experiments gave 18'2 minutes as the 

 length of this interval. 



It is not possible to determine with exactitude the average length 

 of this period in man, but in the case given it was fifteen minutes, in 

 another instance reported by the same observer it was an hour and 

 fifteen minutes ; and an eye-witness, who evidently described a case 

 with great accuracy as to details, stated four hours passed before any 

 change was noticed. The evidence available on the subject makes it 

 probable that an interval of an hour is the average of this period in 

 man. 



This pause, it can be proved, depends on two separate factors. The 

 one factor is the time required for the absorption of the poison ; for it 

 is lessened by the poison being injected simultaneously into several 

 different sites. The other is clearly dependent on some secondary 

 change produced by the poison for which time is necessary ; for if the 

 part into which the poison has been injected be excised before the 

 occurrence of a single constitutional symptom, yet, nevertheless, the 

 animal may die apparently as rapidly as if no interference had been 



