THE LEUCOCYTES IN IMMUNITY. 



741 



combine with the complement, a much higher temperature is 

 necessary." 



In the light of our conception of the functions of the red 

 corpuscles i.e., that it is merely a carrier of haemoglobin, from 

 which the serum can replenish itself with oxidizing substance 

 as fast as this is used the relationship between cell and oxidiz- 

 ing substance, or intermediary substance, logically coincides 

 with the observations of Ehrlich and Morgenroth. The sub- 

 stance simply adheres to its feeder regardless of the tempera- 

 ture. Not so with the trypsin-laden alexin, however, for here 

 the temperature-ratios of its trypsin and of the oxidizing sub- 

 stance are, as we have seen, practically co-equal, and, as trypsin 

 requires a certain temperature to insure adequate functional 

 activity, its 0-substance, the oxidizing substance, must itself 

 be brought to this temperature: i.e., the "much higher tem- 

 perature" to which Ehrlich and Morgenroth refer. We have 

 seen how this purpose is reached, viz.: mainly by the phos- 

 phorus (absorbed by the leucocytes from the alkaline phos- 

 phates of the plasma) in the fibrinogen, 78 the blood's own source 

 of heat. The direct part played by the fibrinogen and oxidizing 

 substance in the haemolytic process has caused some investiga- 

 tors to term "hasmolytic complement" the bodies which are 

 constantly present in the blood-stream and increase in quantity 

 when toxics are administered: i.e., these two substances. It 

 now seems obvious that, although they do take part in the 

 hsemolytic process, they are only heat-producing auxiliaries, 

 the true haemolytic substance being the trypsin. 



But the process involves the necessity of a mechanical 

 combination capable of insuring the presence in the blood- 

 stream of just enough trypsin to correspond with the fibrinogen 

 in the blood-stream. How could this object be better subserved 

 than, as is the case, by combining in the same cell, the neutro- 

 phile leucocyte, the two active constituents? Again, what more 

 precise mechanism could we obtain than a granule of fibrinogen 

 stopping up, as it were, a canaliculus leading up to the central 

 or perinuclear vacuole in which the trypsin is stored and sud- 



78 We must emphasize the fact that the term "flbrinogen," as we understand 

 it, is not intended to represent the body recognized as such by physiological 

 chemists, though considerable kinship between the two exists. S. 



