PHOSPHOROUS SUBSTANCES OF THE CELL. 141 



of protamines or they exist in the free state. Their simplest 

 compounds with proteids form the group of the nuc/eins, a 

 name first applied to the substance isolated by Miescher 

 from the nuclei of pus cells, being the residue left on sub- 

 mitting the cells to gastric digestion. The nucleins are 

 found to be present in nearly all cells, though not in a free 

 state, but combined with a further amount of proteid to form 

 the group of bodies termed the nucleo-proteids. The nucleo- 

 proteids react as weak acids whose neutral alkaline salts are 

 soluble in water and coagulate on heating. If the solution 

 or the heat coagulum be digested with artificial gastric juice 

 most of the proteid is split off and dissolved leaving an in- 

 soluble residue, the nuclein. From the nuclein, as Altmann 

 showed, we can, by the use of alkali, split off a further 

 amount of proteid and thus obtain the nucleic acid. The 

 nucleo-proteids are at present regarded as the most 

 characteristic proteids obtainable from nuclei. 



Closely related to the nucleins is another group of bodies 

 containing phosphorus and showing many other points in 

 common but differing in that they do not contain any 

 nuclein base. To this group of bodies Kossel gives the 

 name of paranuclein but for them Hammarsten 1 suggests 

 as a more satisfactory term the name pseudo-nuclein. As 

 the nucleins are found in the cell or nucleus combined with 

 proteids as nucleo-proteids, so the paranucleins are also 

 found combined with proteids. To these proteids Ham- 

 marsten suggests that the name of nucleo-albumins should 

 be limited. Examples of the nucleo-albumins are casein 

 and ovo-vitellin. 



On artificial gastric digestion they leave an insoluble 

 residue of paranuclein, but if the digestive fluid be strong the 

 paranuclein gradually dissolves. The amount of phosphorus 

 found in solution varies with the strength of the digestive 

 fluid and with a smaller amount of the nucleo-albumin 

 submitted to digestion. As a nuclein is split up into 

 nucleic acid and a proteid so a paranuclein breaks down 

 into a proteid and paranucleic acid, but this latter has not 

 yet been much examined. Kossel and Neumann consider 



1 Hammarsten : Ztschr. f. physiol. Chem., Bd. 19, S. 19, 1894. 



