THE NUCLEINS. 65 



different in its characters from the one just described. H. Weydemann 1 has 

 also confirmed Pavy's work; he considers that the material in the proteid 

 that yields the reducing substance is identical with Landwehr's animal gum. 



The nucleins. Lander Brunton 2 described the nuclei of the red 

 corpuscles of birds as consisting of a mucin-like substance. Plosz, 3 

 however, found that, though the material in question resembled mucin 

 in its solubility in alkalis, and precipitability by acids, it was not mucin, 

 as it contains a high percentage of phosphorus. About the same time 

 Miescher 4 separated a similar phosphorus-rich substance from the nuclei 

 of pus corpuscles ; the pus was subjected to gastric digestion, and the 

 nuclein alone remained undissolvecl. Later, Miescher 5 prepared a similar 

 substance from the spermatozoa of different animals, and from egg-yolk ; 

 Hoppe-Seyler, 6 Kossel, 7 and Loew 8 from yeast, Plosz 9 from the liver, 

 Jaksch 10 and Geoghegan 11 from brain, Lubavin 12 from cows' milk, and 

 Worm-Miiller 13 from egg-yolk. 



It was soon surmised that nuclein is not a single substance, because 

 the different nucleins vary in their solubilities, and even in their compo- 

 sition. Miescher's nuclein from spermatozoa, for instance, contained no 

 sulphur. Of recent years our knowledge of the nucleins has been con- 

 siderably advanced by Kossel, 14 Liebermann, and others. 



It has long been known that metaphosphoric acid is a precipitant 

 of albumin. Liebermann 15 examined this precipitate and found that it 

 gave many of the reactions of nuclein. He therefore came to the con- 

 clusion that nuclein is simply a compound of albumin with phosphoric 

 acid. Malfatti 16 carried this idea still further, for he found that, by 

 fractional precipitation with different amounts of phosphoric acid, he 

 was able to obtain a chain of nucleins with different amounts of 

 phosphorus in each, and with varying solubilities, corresponding closely 

 with those obtainable from nuclei. 



Pohl, 17 however, very soon showed that Liebermann's precipitate 

 differs from true nuclein (i.e. the nuclein from nuclei) in the fact that 

 substances of the xanthine group are not obtainable from it on 

 decomposition, and Kossel 18 has contested Liebermann's and Malfatti's 

 views chiefly on the same grounds. 



Kossel divides the nucleins into two groups. The first is that of 

 the true nucleins. These are obtainable from nuclei ; they yield on 

 decomposition the xanthine bases hypoxanthine, aclenine, and other sub- 

 stances of the same group. The second class of nucleins may be called 

 pseudo-nucleins, and include those obtainable from milk, egg-yolk, 



1 Inaug. Diss., Marburg. 1896 ; Centralbl. f. Physiol., Leipzig, 1897, Bd. x. S. 749. 



3 Journ. Anat. and Physiol., London, 2nd series, vol. iii. p. 91. 



3 Hoppe-Seyler, "Mod! Ohem. Untersuch. , " 1871, Heft 4, S. 460. 4 Ibid., S. 441. 



5 Verhandl. d. naturf. Gesellsch. in Basel, 1874, Heft i. 



G "Med. Chem. Untersuch.," Bd. iv. S. 500. 



7 Ztschr. f. physiol. Chem., Strassburg, Bde. iii. and iv. 



8 Arch.f. d. gcs. Physiol. , Bonn, 1880, Bd. xxii. 9 Ibid., Bd. vii. 



10 Ibid., Bd. xiii. u Ztschr. f. physiol. Chem., Strassburg, Bd. i. 



12 Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. x. S. 2237. 



13 Arch.f. d. ges. Physiol., Bonn, 1873, Bd. viii. S. 190. 



14 Zlschr.f. physiol. Chem., Strassburg. Numerous papers from Bd. viii. to present time. 



15 Ber. d. deutsch. chem. Gesellsch., Berlin, Bd. xxi. S. 598. 



16 Ber. d. naturw.-med. Ver. in Innsbruck, 1891-92, Bd. xx. ; Ztschr. f. physiol. Chem., 

 Strassburg, Bd. xvi. S. 69 ; xvii. S. 8. 



37 Ztschr. f. physiol. Chem., Strassburg, Bd. xiii. S. 292. 



18 Verhandl. d. physiol. Gesellsch., Berlin, Oct. 21, 1892 (in Arch. f. Physiol., Leipzig, 

 1892). 



VOL. I. 5 



