300 COLLECTED STUDIES IN IMMUNITY. 



were unable to obtain a like result in two similar cases. Evidently 

 slight variations in the experiment and possibly also minute changes, 

 and impurities leading perhaps to certain ion actions, play a role which 

 it is difficult to control. We were not interested enough to follow 

 up these relations; but we believe that had we done so we could have 

 made the conditions more favorable for washing out the endocomple- 

 ments. We merely mention this because Flexner and Noguchi state 

 that in their experiments after repeated washings of the blood-cells 

 all of these were found insoluble in cobra poison alone. 



These authors did most of their work with snake poisons differ- 

 ent from ours (Crotalus adamanteus, Ancistrodon contortrix, etc.). 

 How far this fact is responsible for the divergence cannot here be 

 decided, nor whether the escape of the endocomplements was favored 

 by other conditions in the experiments. 1 



That the endocomplements cannot be derived from the serum 

 is also shown by the observation frequently made by us that the serum 

 of several species of blood, whose blood-cells exhibit a plentiful supply 

 of endocomplement, does not possess the slightest activating power, 

 but that, on the contrary (as in the case of rabbit serum) , it sometimes 

 hinders haemolysis of the homologous blood-cells by snake poison. 



So far as the condition is concerned in which the endocomple- 

 ments exist, we must assume, in those cases in which the blood- 

 cells are directly soluble, that the endocomplement is contained 

 free in the blood-cells. In those blood-cells, which are primarily 

 insoluble, it will either be absent or be present in a latent form. 

 We believe the endocomplements are absent in the goat, for in no 

 case were the dissolved goat blood-cells able to activate cobra venom 

 for goat blood. On the other hand, ox blood is sensitized for cobra 

 venom by dissolved ox blood-cells, so that we shall have to assume 

 that ox blood does not contain endocomplements in available form 

 and that these endocomplements are changed into an active form 

 when the cells are dissolved. 



We shall reserve for subsequent study the question as to whether 

 the endocomplements are of simple constitution or complex. 



Attention is called to the fact that the existence of endocom- 

 plements furnishes another objection to Bordet's view that the 



1 We shall merely say that Daboia poison, which through Lamb's pretty 

 experiments has been shown to differ from cobra poison, does not dissolve rabbit 

 blood. 



