254 
Proceedings of Royal Society of Edinburgh. [sess. 
A Research into the Nature of the Nucleins and Para- 
nucleins of the Animal Cell. By T. H. Milroy, M.D., 
B.Sc. 
(Read December 21, 1896.) 
[Abstract.) 
There are two constituents of the cell which have, during the 
last few years, attracted a great deal of attention, namely, the 
nucleins and paranucleins. 
The nucleins are essential constituents of the cell nucleus, appear- 
ing there in different forms of combination. The true nucleins 
possess at least three characters in common. 
In the first place, they have a high percentage of phosphorus. 
Secondly, they offer great resistance to the action of peptic 
digestion. 
Thirdly, they furnish nuclein bases on being subjected to the 
action of weak acids at moderate temperatures (about 100° C.). 
They may be regarded as representing combinations between a 
rich phosphorus-holding acid — nucleic acid — and albumin. These 
combinations may either be of a firm or loose character, that is to 
say, in the case of the former it is difficult to split off the nucleic 
acid from the nuclein by the action of hot saturated baryta 
solutions, while in the latter the decomposition takes place 
easily. 
It seems probable that there are four or more different nucleic 
acids, according as they give on decomposition certain definite 
nuclein bases. In other words, each nuclein base may have its 
corresponding nucleic acid from which it is derived. From this it 
follows that there may be also different nucleins corresponding to 
each nucleic acid. As examples, one may take thymus nuclein, which 
gives in decomposition with weak acids adenin and guanin, while, 
from the nuclein of the pancreas, only guanin has been obtained. 
This acid constituent of the nuclein possesses the property of pre- 
cipitating proteids out of their solutions. It has been regarded as 
not unlikely that these precipitates might be similar to the natural 
