THE ALBUMINOIDS. 69 



If the iron is, as it appears to be, in organic union, the nucleins that 

 contain it must be among the most complex of known organic compounds, 

 consisting of seven elements. 



The exact method in which the iron is combined is however, like the 

 constitution of nuclein, still unknown. 



Zaleski l has succeeded in separating from the liver one of these iron-con- 

 taining nucleins, which he terms liepatin. The subject has been largely worked 

 by microchemical methods for the detection of iron ; and the terms " firmly 

 combined" and "loosely combined" iron are often used, according as the com- 

 pounds which contain that element give the reactions with difficulty or ease. 

 Macallum 2 finds that the chromatin of nuclei contains iron ; he regards 

 it as the mother substance of haemoglobin, both in embryological develop- 

 ment and during nutrition in extra-uterine life. He finds similar haematogens 

 in plants, as did also Bunge. 



Lecith - albumins. Liebermann 3 has given the name lecith-albu- 

 mins to certain compounds of lecithin and proteid which he obtained from 

 the kidney, gastric mucous membrane, lungs, spleen, and liver. The 

 lecithin is not removable from these compounds by simple extraction 

 with alcohol and ether. These, however, can hardly be considered to 

 be immediate constituents of the cells, as they are obtained after sub- 

 jecting them to a very severe process, namely, artificial gastric digestion. 

 They yield no phosphoric acid and no xanthine bases on decomposition. 

 According to their discoverer, they play an important part (in virtue of 

 the acidity which they possess in common with nuclein compounds) in 

 the separation of the hydrochloric acid of the gastric juice, and in decom- 

 posing the alkaline salts of the blood plasma, so as to yield the acid 

 salts of the urine. Much more extended investigations are needed, 

 however, before important functions like these can be safely attributed 

 to them. 



We have already seen that vitellin is a proteid which by some is 

 regarded as a globulin, by others as a nucleo-proteid. Hoppe-Seyler 4 was 

 inclined to regard the phosphorus found in it as due to a combination 

 with lecithin, whereas Hammarsten looks upon some forms of vitellin as 

 phospho-gluco-proteids. No doubt, vitellin is a name which covers a 

 number of different substances; the substance Hoppe-Seyler worked 

 with contained as much as 25 per cent, of lecithin. In those cases 

 where the phosphorus is present as a nuclein, the nuclein obtained by 

 gastric digestion is of the pseudo-nuclem variety. 



THE ALBUMINOIDS. 



The albuminoids form a heterogeneous group of substances allied to 

 the proteids, but differing from them by certain marked characteristics. 

 As a rule, they are found in skeletal and epidermal structures, and 

 usually they are remarkable for their resistance to reagents. They 



1 Ztschr. f. physiol. Chem., Strassburg, Bd. x. S. 453 ; xiv. S. 274 ; Chem. Centr.-BL, 

 Leipzig, 1888, S. 759. See also Quincke, Deutsches Arch. f. klin. Med., Leipzig, Bd. xxv. 

 S. 567 ; xxvii. S. 202 ; xxxiii. S. 23 ; Peters, ibid., Bd. xxxii. S. 182. 



' 2 Macallum's most recent papers are in Journ. Physiol. , Cambridge and London, 1894, 

 vol. xvi. p. 268 ; Proc. Roy. Soc. London, 1895, vol. Ivii. p. 261 ; 1. 277 ; Quart. Journ. 

 Mic/r. Sc., London, 1896, vol. xxxviii. p. 175 ; Rep. Brit. Assoc. Adv. Sc., London, 1896. 



3 Arch.f. d. ges. Physiol., Bonn, Bde. 1. and liv. 

 "Med. chem, Untersuch.," 1868; Ztscltr. f. physiol. Chem., Strassburg, Bd, xiii. S, 



