104 Journal of the Mitchell Society [December 



The extent of the temperature elevation is, within certain 

 limits, proportional to the amount of hematin injected. The 

 temperature effect, being very slight with small doses, increases 

 with the dose, until we begin to obtain signs of an over-intox- 

 ication when the elevation may be much less than with smaller 

 doses, the optimum dose usually being between 10 and 15 

 milligrams per kilo of body weight. The elevation of temper- 

 ature obtained with such optimum doses is from 3° to 3.5° F., 

 and it is exceptional that a greater rise is reached. Occasion- 

 ally, however, the temperature may rise 4° F. or even higher 

 in highly susceptible animals. The greatest elevation recorded 

 in my series of experiments was 4.9° F. in animal ISTo. 9, with 

 a dose of 18 milligrams of hematin per kilo. 



In well-marked reactions, the temperature usually returns 

 to within the normal range in the course of three to five hours. 

 With large or initial injections of hematin, the period of 

 elevated temperature is more prolonged than under other 

 circumstances and seldom reaches normal in less than four 

 hours, occasionally requiring as much as six hours. Excep- 

 tionally, the return to normal may be rapid (text-figure 3). 



The method of administration also plays an important part 

 \n the results. A given dose of hematin injected in two or three 

 fractional doses at intervals of fifteen to thirty minutes produces 

 a much more marked elevation of temperature than when given 

 at a single injection, an effect that is well sho-\vn in rabbit 13. 

 This is particularly true of the smaller, or optimum doses, 

 while with larger doses the increased potency may be man- 

 ifested by a slowing of the rise of temperature, a cessation of 

 the rise, or even a fall upon the injection of the second fraction, 

 as illustrated in rabbit 12. 



Neither the source of the hematin nor the type of solution 

 seems to play an important part in the results that I have ob- 

 tained. That is, there has been but slight difference between 

 the action of rabbit, dog, or ox hematin, or between the action 

 of the perfectly clear hematin solution and that containing 

 much finely divided hematin in suspension. 



However, a few tests seem to indicate that solutions of hem- 



