256 Proceedings of Royal Society of Edinburgh. [sess. 
Nucleic acid seems to have the power of uniting with varying 
quantities of different albumoses, the phosphorus percentage of 
those bodies being, as a rule, higher than that of the syntonin 
nuclein. 
In order to compare these artificially-formed nucleins with the 
natural ones, I shall sum up very shortly some of the results 
derived from investigations which I have made into the nature of 
the latter class of proteids. 
The nuclein present in the thymus gland was found to contain 
about 4*5 per cent, phosphorus. Even very prolonged subjection 
(10 hours) to the action of the gastric juice had only the effect of 
diminishing to a very slight extent this percentage. Here, how- 
ever, as in the case of the syntonin nuclein, there was a gradual 
solution of the thymus nuclein, the phosphorus appearing in 
organic combination among the soluble products of digestion. 
Trypsin and sodium carbonate (0*25 per cent.) rapidly split up 
this nuclein, the phosphorus percentage falling after four hours’ 
digestion with pancreatic extract from about 4*5 to 1*8 per cent. 
A proteid precipitating body is present among the soluble diges- 
tion products. 
In the case of the thymus nuclein, the combination between 
nucleic acid and the albumin is a loose one. 
The nucleins of the red blood corpuscles of various birds and 
also that of the pancreas were examined in the same way. 
All are characterised by the resistance which they offer to 
peptic digestion, and the ease with which the pancreatic extract 
splits them up. 
The combinations between the acid and albuminous radicles are 
in both cases of a firm description. 
The paranucleins can only be defined in rather an indefinite 
way. They possess a high percentage of phosphorus, which is 
present in organic combination. We always find the paranuclein 
united in the tissues to a variable amount of proteid, which is 
removable by the action of the gastric juice. Examples of these 
combinations are casein and ovovitellin. 
The paranucleins do not offer so great resistance to the action 
of the peptic ferment as the nucleins. They do not, on decom- 
position with acids, furnish nuclein bases. 
