Sentence:  It is interesting to find that, with the exception of a few imperfectly-observed South Sea Islanders, and whose actual numbers, if the measurements are correct, are very few, the English professional classes head the long list [in average height], and that the Anglo-Saxon race takes the chief place in it among the civilised communities, although it is possible it might stand second to the Scandinavian countries if a fair <WSD>sample</WSD> of their population were obtained. 
Meaning of the word marked with <WSD> tags:  A subset of a population selected for measurement, observation or questioning, to provide statistical information about the population.