Sentence:  This was later <WSD>known</WSD> to be the result of concentrating the minute amount of complete antibody found in these sera ; when the insoluble fraction was suspended in a volume of saline equal to that of the original serum sample , no complete antibody activity could be detected . 
Meaning of the word marked with <WSD> tags:  accept (someone) to be what is claimed or accept his power and authority