2o 4 SCIENCE PROGRESS 



ether ; by this means the envelopes of the corpuscles were 

 ruptured, the contents escaped, the haemoglobin passed into 

 solution, and the nuclei were found floating at the junction 

 of the two fluids. Some subsequent methods of washing to 

 free them from adhering impurities were then adopted, and 

 finally the reactions and composition of the resulting material 

 were examined. Brunton finally arrived at the conclusion 

 that the substance of which the nuclei are composed was 

 mucin. This was incorrect, but the mistake was pardonable 

 in those early days of physiological chemistry. At that period 

 the truth of the proverb "All that is sticky is not mucin" 

 was not recognised ; and since that time the viscous material 

 in the bile which used to be regarded as mucin has been 

 shown to be a nucleo-protein, in certain animals at any rate. 

 Mucin and nuclein or nucleo-protein are not only often 

 alike in physical consistency, but both of them contain a 

 carbohydrate complex, both are soluble in dilute alkali and 

 precipitable therefrom by acetic acid. In spite of these 

 similarities the two substances are not identical, and one 

 difference, the presence of phosphorus in the nucleic compound, 

 was discovered by Plosz, who later on repeated Brunton's 

 experiments. 



In the same year in which Plosz performed this work 

 (1871), Miescher, Professor of Physiology at Basle, published 

 a memorable paper on the nuclei of pus corpuscles. He made 

 the fortunate observation that on subjecting cells to the 

 action of artificial gastric juice, the protoplasm was dissolved 

 and the nuclei were unaffected, and to the material, rich in 

 phosphorus, which he separated out from the nuclei he gave 

 the name nuclein. Plosz, knowing of this work, surmised 

 correctly that the mucin of Brunton was of a similar nature. 



Miescher was rash enough at the time to ascribe an 

 empirical formula to his nuclein, namely C 2 aH49N 9 P 3 22 , which 

 he calculated from the percentage composition. He subse- 

 quently put forward a revised formula, and numerous others 

 have been suggested by later workers. For it was found 

 that nucleins of different origin presented great divergencies 

 on elementary analysis. It was therefore supposed that there 

 are different kinds of nuclein, differing not only in the 

 quantity or kind of protein in their molecules, but also in 

 the nature of their nucleic acid component. 



