THE PHENOMENA OF ADSORPTION. 459 



of the two sera diluted each with an equal amount of salt solution, 

 the corpuscles react very much as they do in a fresh mixture. 



Ehrlich's theories would feel no embarrassment in face of such 

 a fact. To explain it, we may suppose that bovine serum con- 

 tains several amboceptors, among which are some with no affinity 

 for the guinea-pig corpuscles. Such amboceptors, if time were 

 given them, would monopolize the alexin, would deviate it, and 

 prevent it from uniting with the guinea-pig corpuscle. If the 

 experimental result had turned out in the opposite way, the same 

 theories would still be satisfied. It would suffice to say simply 

 that the bovine amboceptor which combines with the guinea-pig 

 corpuscles shows a greater affinity when it has had time to unite 

 previously with alexin. As we have already seen, Sachs and Bauer 

 have suggested this interpretation in similar experiments which 

 prove to them in some inexplicable manner that a prolonged con- 

 tact exaggerates the activity of a mixture instead of diminishing 

 it.* As long as one has recourse to such purely hypothetical ideas, 

 which may be varied and multiplied as one desires, it is clear that 

 any experimental fact may be interpreted. The statement that 

 the amboceptor has a complementophilic group is a hypothesis. 

 The statement that the affinity of this group varies with different 

 amboceptors is another hypothesis; the supposition that the cyto- 

 philic group becomes chemically more active when affinities of 

 the complementophilic group are satisfied is a third hypothesis. 

 A theory is of service only when used to coordinate real and demon- 

 strated facts; it is of no value when it unites hypothetical facts 

 produced, created and fashioned at the will of the theorist, with 

 a single demonstrated fact. 



The question of the mutual relations between the sensitized 

 corpuscle, the alexin and the conglutinin should be subjected to 

 additional researches in order to be quite clear. It seems, how- 

 ever, that to obtain the maximal effect of agglutination, and par- 

 ticularly of hemolysis, the order in which the three substances 

 are added should be kept in mind. If the conglutinin and alexin 

 are added in certain proportions and an interval allowed to elapse 



* Sachs and Bauer's mixtures, to be sure, contained relatively more horse 

 serum than ours. We have not, however, been able to produce their results even 

 by following their experiment closely. 



