CHEMISTRY OF THE CELL NUCLEUS 207 



be regarded as identical. For the work which has been 

 instrumental in reducing confusion to order we have to 

 thank Schmiedeberg and Steudel in Germany, Ivar Bang in 

 Sweden, and Walter Jones and Levene in America. 



Schmiedeberg from careful analyses has been able to give 

 an empirical formula for the acid which is probably nearer 

 the truth than Miescher's ; Levene and Mandel have advanced 

 views as to its constitution which, though useful as a basis 

 for renewed work, should be regarded more safely as pro- 

 visional than final. Schmiedeberg also in his work drew 

 attention to a distinction between what he regards as the 

 hydrated and anhydrous forms of the acid, and to the power 

 which the latter possesses of gelatinising. The recognition 

 of a gelatinous or colloidal condition sometimes presented 

 by nucleic acid and its salts is of importance, whether the 

 explanation that the absence or presence of water in the 

 molecule is the correct one or not. Jones pointed out that 

 in the case of the sodium salt the gelatinous and non-gelatinous 

 varieties are easily convertible one into another, and this 

 reversible action is believed by him to be a simple explanation, 

 if it occurs in vivo of the physiological localisation and migra- 

 tion of nucleic acid. 



Bang's work was previous to that of both Schmiedeberg 

 and Jones. He prepared from the pancreas a nucleic acid 

 which is much simpler in composition than the majority of 

 those previously isolated. It yields on decomposition only 

 three substances, namely, phosphoric acid, a sugar of the 

 pentose group, and one purine base, namely guanine. For 

 this reason he bestowed upon it the name of guanylic acid. 

 This has been confirmed by Steudel, Levene and others, and 

 guanylic acid has been found in other organs, for instance the 

 liver. Both liver and pancreas, however, contain in addition 

 what may be termed ordinary nucleic acid, which yields on 

 cleavage additional products. 



The discovery of guanylic acid at first seemed to complicate 

 the subject, but really it helped to simplify it, for there is no 

 doubt that the older workers had investigated mixtures of 

 nucleic acid proper and guanylic acid, and thus obtained 

 divergent analytical results. 



We need not, however, follow out in detail the curious 

 comedy of errors which led to previous confusion ; this has 



