Sentence:  An arsphenamine is regarded as "<WSD>hyperideal</WSD>" if of the five injected with the 1 in 300 dilution, four survive; of the five injected with the 1 in 275 dilution, three survive; and of the five injected with the 1 in 250 dilution, two survive. 
Meaning of the word marked with <WSD> tags:  Extremely close to the ideal.