THE NU CLE INS. 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. — Lauder 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 undissolved. Later, Miescher 5 prepared a similar 
substance from the spermatozoa of different animals, and from egg-yolk; 
Hoppe-Seyler, 6 Kossel, 7 and Loew s from yeast, Plosz 9 from the liver, 
Jaksch 10 and Geoghegan 11 from brain, Lubavin u from cows' milk, and 
Worm-Muller 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 1S 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, adenine, 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. 
2 Journ. Anat. and Physiol., London, 2nd series, vol. iii. p. 91. 
3 Hoppe-Seyler, ''Med. Chem. Untersuch.," 1871, Heft 4, S. 460. 4 Ibid., S. 441. 
3 Verhandl. d. naturf. Gesellsch. in Basel, 1874, Heft i. 
fi "Med. Chem. Untersuch./' Bd. iv. S. 500. 
7 Ztschr. f. physiol. Chem., Strassburg, Bde. iii. and iv. 
s Arch.f. d. ges. Physiol., Bonn, 1880, Bd. xxii. 9 Ibid., Bd. vii. 
10 Ibid., Bd. xiii. n Ztschr. f. physiol. Chem., Strassburg, Bd. i. 
12 Per. d. deutsch. chem. Gesellsch., Berlin, Bd. x. S. 2^:J7. 
13 Arch.f. d. ges. Physiol., Bonn, 1873, Bd. viii. S. 190. 
14 Ztschr. f. physiol. Chem., Strassburg. Numerous papers from Bd. viii. to present time. 
10 Per. d. deutsch. cliem. Gesellsch., Berlin, Bd. xxi. S. 598. 
16 Per. d. naturw.-med. Ver. in Innsbruck, 1S91-92, Bd. xx. ; Ztschr. f. physiol. Chem., 
Strassburg, Bd. xvi. S. 69 ; xvii. S. 8. 
17 Ztschr. f. physiol. Chem., Strassburg, Bd. xiii. S. 292. 
18 Verhandl. d. physiol. Gesellsch., Berlin, Oct. 21, 1892 (in Arch. f. Physiol., Leipzig, 
1892). 
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