136 PROTEIN POISONS 



therefore, the best index which we have as to the exact 

 time at which the poison begins to exert its effect. In the 

 same manner the rise of temperature after the development 

 of hypothermia is the first indication of recovery. More- 

 over, if in an animal with a subnormal temperature a rise 

 occurs, it is an infallible sign of ultimate recovery, no matter 

 how grave the general condition may appear to be at the 

 time. We have laid great stress, therefore, on the changes 

 in body temperature as furnishing the most delicate test 

 of the action of the poison. It may be here stated that 

 the body temperature of guinea-pigs is ordinarily fairly 

 constant within certain narrow limits, and they are much 

 more satisfactory animals to work with in this respect 

 than are rabbits. Moreover, their temperature does not 

 seem to be materially altered by the injections of sterile 

 salt solution or such inert substances as a suspension of 

 pumice stone into the peritoneal cavity. As has been seen 

 in the case of the living germ, it is only after the lapse of 

 several hours that a fall in temperature occurs. This 

 would indicate that it is not until this time that sufficient 

 poison is liberated to cause notable toxic effects in the 

 animal. That it takes an appreciable time for the poison 

 to be liberated from the bodies of the bacilli is well illus- 

 trated in the instance of the dead bacterial substance. 

 Here it is only a question of dissolution of the bacilli and 

 the setting free of the contained poison, and yet it will 

 be noticed that an interval of at least two hours and usually 

 longer elapses before there is any noticeable fall in temper- 

 ature. The maximum effect in this case is reached between 

 four and six hours, and if the dose has been a non-fatal 

 one, recovery begins at the end of from eight to ten hours, 

 as is indicated .by the upward trend of the temperature 

 curve at this point. In the case of the soluble poison, the 

 toxic effect begins at once. Within fifteen minutes the 

 temperature has begun to drop and within an hour has 

 reached a minimum. Recovery then begins and within 

 three hours the effect of the poison has worn off, as is best 

 evidenced by the return of the body temperature to normal 

 or above by this time. 



