1912^ Malarial Pigment in Malarial Pakoxtsm 105 



atin gradually lose their pjrogenic properties with age or when 

 subjected to high and prolonged temperature. This apparent 

 decrease may be seen by comparing the results obtained in 

 rabbit 7, injection 3, and rabbits 8, 10, and 11. Further, it 

 can readily be imagined that all animals will not be found 

 equally susceptible to the toxic action of hematin. A few will 

 exhibit a marked sensitiveness and a few will be found ex- 

 tremely resistant, the optimum dose in the one producing but 

 silight effect in the other. This variation in susceptibility was 

 strikingly illustrated by animals 13 and 14 which were under 

 observation at the same time. Rabbit 13 was a typically resist- 

 ant animal, and rabbit 14 was highly sensitive. 



Effect of Sodium Bicarbonate Salt Solution upon the Tem- 

 perature. — Animals injected with the bicarbonate salt solution 

 alone, for purposes of control, almost invariably showed an 

 elevation of temperature in proportion to the size of the dose, 

 and about one-third to one-half the elevation produced with an 

 equal amount of hematin solution, depending somewhat upon 

 the concentration of the hematin in the solution. With small 

 doses of the control medium, the fluctuations of temperature 

 were usually within what might be termed the normal range 

 and were such that it is difficult to say whether they are more 

 than incidental to the process of injection. Large doses may 

 produce a rise in temperature corresponding approximately 

 to the over-intoxicating effect of large doses of hematin. In 

 such instances, however, other features of the clinical picture 

 will distinguish sharply between the two cases. In all instances, 

 therefore, there were distinct differences between the action 

 of the sodium bicarbonate salt solution and the action of the 

 hematin solution, such that there can be no question as to the 

 part played by the hematin in these experiments. 



Other Phenomena of the Hematin Paroxysm. — Apart from 

 the elevation of temperature in the experimental animal, the 

 paroxysm of hematin intoxication presents other features 

 which are of equal importance and show a strong resemblance 

 to corresponding phenomena of the malarial paroxysm. For 

 the first fifteen to twenty minutes following the injection of 



